VA Class:CN101

AHFS Class:

• Opioid Partial Agonists 28:08.12

Generic Name(s):

• Buprenorphine

• Buprenorphine Hydrochloride

Chemical Name:

• 6,14-Ethenomorphinan-7-methanol, 17-(cyclopropylmethyl)-α-(1,1-dimethylethyl)-4,5-epoxy-18,19-dihydro-3-hydroxy-6-methoxy-α-methyl-, [5α,7α,(S)]

• [5α,7α(5)]-17-(Cyclopropylmethyl)-α-(1,1-dimethylethyl)-4,5-epoxy-18,19-dihydro-3-hydroxy-6-methoxy-α-methyl-6,14-ethinomorphinan-7-methanol hydrochloride

Molecular Formula:

• C₂₉H₄₁NO₄

• C₂₉H₄₁NO₄•HCl

Buprenorphine is a synthetic opiate partial agonist analgesic.1,6,7,10,11,202,213,214

Buprenorphine hydrochloride is used parenterally for the relief of pain that is severe enough to require opiate analgesia and for which alternative treatment options are inadequate.1,124,183,185 Buprenorphine hydrochloride also is used buccally and buprenorphine is used transdermally for the management of pain that is severe enough to require daily, around-the-clock, long-term opiate analgesia and for which alternative treatment options are inadequate.213,232

In the management of opiate dependence (opiate use disorder [OUD]), buprenorphine is used parenterally as an extended-release subcutaneous injection,236 buprenorphine hydrochloride is used sublingually or as a subdermal implant,233,237 and buprenorphine hydrochloride in fixed combination with naloxone hydrochloride is used sublingually or buccally.202,214,234,235

Pain

Parenteral Therapy

Buprenorphine hydrochloride is used parenterally as an analgesic for the relief of pain that is severe enough to require an opiate analgesic and for which alternate treatments are inadequate;1,124,183,185 because of the risks of addiction, abuse, and misuse associated with opiates even at recommended dosages, parenteral buprenorphine should be reserved for use in patients for whom alternative treatment options (e.g., nonopiate analgesics, opiate-containing fixed combinations) have not been, or are not expected to be, adequate or tolerated.1 The analgesic activity of 0.3 mg of parenteral buprenorphine is about equal to that of 10 mg of parenteral morphine sulfate21,97,185 or 75-100 mg of parenteral meperidine.21,79,184 In equianalgesic doses, parenteral buprenorphine generally appears to be as effective as23,44,53,60,71,77,79,80,82,96,97,99,105,106,140,145,184 or possibly slightly more effective71,75,98,99,103,151,184,185 than parenteral morphine,23,44,53,60,71,75,77,82,96,97,99,103,106,140,145,185 meperidine,71,80,98,103,151,184 or pentazocine57,71,79,105,151 in relieving moderate to severe pain. The duration of analgesia produced by a single dose of parenteral buprenorphine is generally longer than that produced by a single parenteral dose of meperidine21,71,80,98 or pentazocine21,48,71,177 and is comparable to128,145,185 and, in some patients, may be longer than that produced by a single parenteral dose of morphine.21,71,82,97,128,152,177,185

Buprenorphine is used parenterally in the management of postoperative pain in patients who have undergone various types of surgery, including neurologic,138 cardiovascular (e.g., coronary artery bypass, valve replacement),66,71,185 cesarean section,28,71,82,110 gynecologic,28,60,69,71,80,124,149,151,177 abdominal (e.g., cholecystectomy, bowel resection),28,32,44,54,64,69,71,73,76,103,145,151,184,185 urologic,28,124,185 general (e.g., head and neck, breast),53,60,151 and orthopedic (e.g., total hip replacement, spinal fusion).23,26,32,83,92,145,185 Because of its limited cardiovascular effects, buprenorphine may be safer than morphine when used as an analgesic in patients with compromised cardiac function undergoing cardiovascular surgery.66,71,141 The drug has also been administered by epidural injection† in the management of postoperative pain in total dosages substantially less than the equivalent morphine dosages necessary to produce a comparable analgesic effect.23,30 Buprenorphine has also been used to provide preoperative sedation and analgesia†35,58,60,127,140,148 and as an adjunct to surgical anesthesia†;24,49,58,60,62,71,121,135,142,149,192 however, the drug should be used with caution in patients undergoing surgery of the biliary tract.54

Buprenorphine has been used parenterally as an analgesic for the relief of moderate to severe pain associated with cancer31,65,71,99,134,143 and trigeminal neuralgia.47 The drug has also been used as an analgesic in critically ill patients for the relief of moderate to severe pain resulting from accidental trauma73 and as an analgesic for the relief of moderate to severe pain resulting from ureteral calculi.98 Buprenorphine has also been used as an analgesic for the relief of moderate to severe pain associated with myocardial infarction.71,150

Transdermal Therapy

Buprenorphine is used transdermally for the management of pain that is severe enough to require daily, around-the-clock, long-term opiate analgesia and for which alternative treatment options are inadequate.213 Because of the risks of addiction, abuse, and misuse associated with opiates, even at recommended dosages, and because of the greater risks of overdosage and death associated with extended-release opiate formulations, transdermal buprenorphine should be reserved for use in patients for whom alternative treatment options (e.g., nonopiate analgesics, immediate-release opiates) are inadequate or not tolerated.213 Transdermal buprenorphine is not intended for use on an as-needed (“prn”) basis.213

The safety and efficacy of transdermal buprenorphine have been evaluated in 4 double-blind, controlled trials of 12 weeks' duration.213 Two studies, one in patients with chronic low back pain and one in patients with osteoarthritis, failed to show efficacy for either transdermal buprenorphine or the active comparators.213 Efficacy and safety of transdermal buprenorphine were established in 2 studies in patients with moderate to severe chronic low back pain, including one study in adults not previously receiving opiates and one study in adults receiving chronic opiate therapy at a dosage equivalent to 30-80 mg daily of oral morphine sulfate.213,223 Chronic opiate regimens were tapered prior to initiating buprenorphine.213,223 Both studies utilized an initial open-label dose titration period of up to 3-4 weeks; buprenorphine was initiated at a dosage of 5 mcg/hour (or 10 mcg/hour in those previously receiving opiate treatment) and increased at intervals of at least 72 hours to a maximum dosage of 20 mcg/hour.213,223 Patients who achieved adequate analgesia with tolerable adverse effects (approximately 53-57% of patients) during this phase were randomized to 12 weeks of double-blind treatment.213,223 In patients who had not previously received opiates for analgesia, transdermal buprenorphine was more effective than placebo in reducing 24-hour average pain scores (measured on an 11-point numeric rating scale).213 Patients who previously had received opiates for analgesia also achieved greater reductions in 24-hour average pain scores with 20 mcg/hour of transdermal buprenorphine when compared with 5 mcg/hour of transdermal buprenorphine (low-dose control).213,223

Oral Transmucosal Therapy

Buprenorphine is used buccally for the management of pain that is severe enough to require daily, around-the-clock, long-term opiate analgesia and for which alternative treatment options are inadequate.232,240,241 Because of the risks of addiction, abuse, and misuse associated with opiates, even at recommended dosages, and because of the greater risks of overdosage and death associated with long-acting opiate formulations, intrabuccal buprenorphine should be reserved for use in patients for whom alternative treatment options (e.g., nonopiate analgesics, immediate-release opiates) are inadequate or not tolerated.232 Intrabuccal buprenorphine is not intended for use on an as-needed (“prn”) basis.232

The safety and efficacy of intrabuccal buprenorphine have been evaluated in 3 double-blind, controlled trials of 12 weeks' duration in patients with moderate to severe, chronic low back pain.232 One study failed to show efficacy.232 Efficacy and safety of intrabuccal buprenorphine were established in 2 studies, including one study in adults not previously receiving opiates and one study in adults receiving long-term opiate therapy at a dosage equivalent to 30-160 mg daily of oral morphine sulfate.232,240,241 Opiate regimens were tapered to a dosage equivalent to 30 mg daily of oral morphine sulfate prior to initiating buprenorphine.232,241 Both studies utilized an initial open-label dose-titration period with buprenorphine of up to 8 weeks' duration.232,240,241 Patients who achieved adequate analgesia with tolerable adverse effects (61-63% of patients) during this phase were randomized to 12 weeks of double-blind treatment with buprenorphine or placebo.232,241 In patients who had not previously received opiates for analgesia, intrabuccal buprenorphine was more effective than placebo in reducing mean pain scores (as measured on an 11-point numeric rating scale), and a greater proportion of buprenorphine-treated patients compared with placebo recipients achieved at least a 30% reduction in pain score (62 versus 47%) or at least a 50% reduction in pain score (41 versus 33%) from baseline (prior to the open-label titration period) to end of study.232,240 In patients who previously had received opiates for analgesia, intrabuccal buprenorphine also was more effective than placebo in reducing mean pain scores, and a greater proportion of buprenorphine-treated patients compared with placebo recipients achieved at least a 30% reduction in pain score (64 versus 31%) or at least a 50% reduction in pain score (39 versus 17%) from baseline (prior to the open-label titration period) to end of study.232,241

Oral transmucosal formulations of buprenorphine or buprenorphine in fixed combination with naloxone that are intended for use in the treatment of opiate dependence should not be used for analgesia.202,214,233,234,235 Fatal overdosage has been reported following administration of 2 mg of sublingual buprenorphine for analgesia in opiate-naive individuals.214,233

For further information on the role of opiate analgesics in the management of acute or chronic pain, see Uses: Pain, in the Opiate Agonists General Statement 28:08.08.

Opiate Dependence

Buprenorphine is used parenterally as an extended-release subcutaneous injection,236 buprenorphine hydrochloride is used sublingually or as a subdermal implant,233,237 and buprenorphine hydrochloride in fixed combination with naloxone hydrochloride is used sublingually or buccally for the treatment of opiate dependence (opiate use disorder [OUD]);202,214,234,235 buprenorphine has been designated an orphan drug by FDA for this indication.201 Safety and efficacy of transdermal buprenorphine for the management of opiate dependence have not been established.213 In the treatment of opiate dependence, buprenorphine should be used as part of a comprehensive treatment program that includes counseling and psychosocial support.202,214,233,234,235,236,237,247,248

Buprenorphine and buprenorphine in fixed combination with naloxone (buprenorphine/naloxone) are available in the US for office-based outpatient medication-assisted treatment (MAT) of opiate dependence.202,214 The Drug Addiction Treatment Act of 2000 (DATA 2000) allows qualifying physicians to prescribe and dispense opiates in schedules III, IV, and V of the Federal Controlled Substances Act that have been approved by FDA for the management of opiate dependence.205 Prior to passage of this law, opiate dependence treatment could be provided only at specially registered clinics.205 The Comprehensive Addiction and Recovery Act of 2016 (CARA 2016) expands the categories of practitioners recognized under DATA 2000 to include qualifying nurse practitioners and physician assistants.229 Office-based treatment with buprenorphine is intended to increase access to opiate dependence treatment.204 Expansion of the categories of qualifying practitioners is intended to further bridge the gap between MAT providers and individuals seeking such treatment, a particular problem in rural areas.229 In the office-based treatment model, specially trained clinicians may prescribe buprenorphine as a take-home medication.204

The choice between buprenorphine and methadone for maintenance treatment of opiate dependence should take into consideration the patient's preferences; the patient's medical, psychiatric, substance use, and treatment histories; and treatment availability and setting.247,248 Buprenorphine is preferred for many patients because it can be prescribed in an office-based setting and is considered to have a better safety profile than methadone.248,259,260 Methadone may be preferred for patients who would benefit from daily supervised dosing in an opiate treatment program and for those who do not have access to, or have not benefited from, buprenorphine therapy.247 Office-based treatment may not be suitable for patients with other concurrent substance use disorders or for those routinely using other CNS depressants.247

Oral Transmucosal Therapy for Induction and Maintenance Treatment

Buprenorphine and buprenorphine/naloxone are used sublingually or buccally for the treatment of opiate dependence.202,214,233,234,235 Although buprenorphine traditionally has been considered the preferred drug for the initial (i.e., induction) phase of treatment,233,250 additional experience indicates that either buprenorphine or buprenorphine/naloxone may be used for induction therapy in patients dependent on heroin or other short-acting opiates.214,234,235,247,250 Use of buprenorphine/naloxone for the induction phase of treatment in patients dependent on long-acting opiates has not been evaluated to date in adequate and well-controlled studies, and the manufacturers and some experts still recommend use of buprenorphine alone for induction in these patients.214,234,235,247,259 Following induction, buprenorphine/naloxone is the preferred drug for maintenance treatment when use includes unsupervised administration since the presence of naloxone (an opiate antagonist) in the formulation should discourage parenteral misuse of the oral transmucosal preparation.202,233 Administration of buprenorphine without naloxone in an unsupervised setting should be limited to pregnant women and patients who cannot tolerate naloxone.202,233,247,254,256

Sublingual buprenorphine and buprenorphine/naloxone have been evaluated in several placebo- and active-controlled studies in patients physically dependent on opiates.200,202,209,210 In these studies, buprenorphine therapy has been used in conjunction with psychosocial counseling as part of a comprehensive addiction treatment program.202 When administered sublingually, buprenorphine and buprenorphine/naloxone have similar clinical effects.202 Results of a dose-ranging study indicate that sublingual administration of buprenorphine dosages of 6-24 mg daily are effective in the treatment of opiate dependence.202,209 Buprenorphine and buprenorphine/naloxone were more effective than placebo in reducing illicit opiate use, as determined by urine tests for other opiates, in one placebo-controlled study that included patients randomized to receive buprenorphine 8 mg or placebo on day 1, buprenorphine 16 mg or placebo on day 2, and then buprenorphine 16 mg daily, buprenorphine 16 mg in fixed combination with naloxone 4 mg daily, or placebo daily for 4 weeks.202 In another study that included a 16- to 17-week maintenance phase and a 7- to 8-week detoxification phase, buprenorphine generally was more effective than low dosages of methadone hydrochloride (20 mg daily) and as effective as high dosages of methadone hydrochloride (60 mg daily) in reducing illicit opiate use and retaining patients in the program.200,202 In another comparative study, buprenorphine, levomethadyl acetate (no longer commercially available in the US because of potentially severe adverse cardiac effects), and high-dose methadone hydrochloride (60-100 mg daily) were more effective than low-dose methadone hydrochloride (20 mg daily) in reducing illicit opiate use.210

Induction therapy with sublingual buprenorphine/naloxone has been evaluated in 2 blinded, randomized noninferiority studies in a total of 1068 opiate-dependent adults.235,244,245 In both studies, treatment retention rates at day 3 were compared following induction therapy with buprenorphine/naloxone sublingual tablets (Zubsolv^®; total induction dosage of buprenorphine 5.7 mg and naloxone 1.4 mg on day 1 followed by either buprenorphine 5.7 mg and naloxone 1.4 mg or buprenorphine 11.4 mg and naloxone 2.8 mg on day 2) or generic buprenorphine sublingual tablets (total induction dosage of 8 mg on day 1 followed by 8 or 16 mg on day 2).235,244 On day 1, patients received an initial supervised dose of the assigned drug (buprenorphine 1.4 mg and naloxone 0.36 mg or buprenorphine 2 mg); at the investigator's discretion, the remainder of the day 1 dosage was administered in 1 dose or, if the first dose precipitated withdrawal manifestations, in 3 divided doses at intervals of 1-2 hours.235 Because of its higher bioavailability, a Zubsolv^® sublingual tablet containing buprenorphine 5.7 mg and naloxone 1.4 mg provides equivalent buprenorphine exposure and 12% lower naloxone exposure as a Suboxone^® sublingual tablet containing buprenorphine 8 mg and naloxone 2 mg.235,244 In the first study, the treatment retention rate at day 3 was 93% for patients receiving buprenorphine/naloxone compared with 92% for those receiving buprenorphine alone;235,244 in the second study, treatment retention rates at day 3 were 85 and 95%, respectively.235 The lower retention rate observed with the fixed-combination preparation compared with buprenorphine alone in the second study may have been related to infrequent use of divided dosing in this study (5%) compared with the first study (22%).235

Maintenance Treatment with Buprenorphine Extended-release Subcutaneous Injection

Buprenorphine extended-release subcutaneous injection is used for the treatment of moderate to severe opiate dependence in patients who have initiated treatment with an oral transmucosal buprenorphine-containing preparation followed by dosage adjustment for a minimum of 7 days.236

Buprenorphine extended-release subcutaneous injection has been evaluated in an opiate challenge study and in a randomized, double-blind, placebo-controlled clinical trial.236,243

In the opiate challenge study, efficacy of buprenorphine extended-release subcutaneous injection in blocking subjective opiate effects following hydromorphone challenge was assessed in 39 individuals with moderate to severe opiate use disorder who were not seeking treatment.236,243 Following stabilization on sublingual buprenorphine/naloxone over one week, study participants received two 300-mg subcutaneous doses of extended-release buprenorphine given 4 weeks apart.236,243 “Drug liking” scores (measured on a 100-mm visual analog scale) following challenge with placebo and hydromorphone hydrochloride (IM doses of 6 and 18 mg) were recorded weekly for 12 weeks after the first buprenorphine injection.236,243 At weeks 1-4, neither hydromorphone dose was substantially more likeable than placebo.236,243 Full blockade of the subjective effects of hydromorphone was observed at both dosage levels during each of the 12 weeks of the study, although substantial variability in isolated measurements from individual study participants was observed.236,243

In the randomized double-blind study, 504 patients seeking treatment for moderate to severe opiate use disorder were randomized to receive buprenorphine extended-release subcutaneous injection (300 mg monthly for 6 months or 300 mg monthly for 2 months followed by 100 mg monthly for 4 months) or placebo following stabilization on buprenorphine/naloxone sublingually dissolving strips.236 Supplemental sublingual doses of buprenorphine/naloxone were not permitted during the study.236 All patients received psychosocial counseling at least weekly. 236 Efficacy was evaluated over weeks 5-24 by means of urine drug testing and self-reports of illicit opiate use.236 Treatment success, defined as opiate-free status for 80% or more of the weeks during the evaluation period, was attained by 28-29% of buprenorphine-treated patients compared with 2% of placebo recipients.236

Maintenance Treatment with Buprenorphine Subdermal Implants

Buprenorphine hydrochloride subdermal implants are used for maintenance treatment of opiate dependence in patients who have achieved and maintained prolonged clinical stability on a low to moderate dosage of an oral transmucosal buprenorphine-containing preparation (i.e., a transmucosal dosage that provides blood buprenorphine concentrations comparable to or lower than those provided by the subdermal implants).237,242 Examples of appropriate dosages of oral transmucosal buprenorphine-containing preparations include the following: Subutex^® sublingual tablets (or generic equivalent; branded formulation no longer commercially available in the US) at a dosage not exceeding buprenorphine 8 mg daily, Suboxone^® sublingual tablets (or generic equivalent; branded formulation no longer commercially available in the US) at a dosage not exceeding buprenorphine 8 mg and naloxone 2 mg daily, Bunavail^® buccally dissolving strips at a dosage not exceeding buprenorphine 4.2 mg and naloxone 0.7 mg daily, and Zubsolv^® sublingual tablets at a dosage not exceeding buprenorphine 5.7 mg and naloxone 1.4 mg daily.237 Buprenorphine subdermal implants are not appropriate for individuals just initiating treatment for opiate dependence or for those who have not achieved and sustained prolonged clinical stability on a low to moderate oral transmucosal dosage of the drug.237

Efficacy of buprenorphine subdermal implants for the maintenance treatment of opiate dependence was established in a randomized, double-blind study in 177 patients who were clinically stable while receiving a sublingual buprenorphine dosage of 8 mg daily or less (as Suboxone^® sublingual tablets or equivalent).237,242 Patients were randomized to receive 4 buprenorphine hydrochloride 80-mg subdermal implants (with daily placebo sublingual tablets) or daily treatment with buprenorphine/naloxone sublingual tablets administered at the prerandomization dosage (with 4 placebo subdermal implants).237,242 Supplemental doses of sublingual buprenorphine/naloxone tablets were permitted as clinically indicated.237,242 In the sublingual treatment group, supplemental dosing was considered consistent with usual treatment, whereas in the implant treatment group, supplemental dosing was interpreted as indicating that the implant dosage was inadequate.237 Efficacy assessments were based on urine drug testing and self-reports of illicit opiate use.237,242 During 6 months of treatment, 63% of patients with subdermal buprenorphine implants (without supplemental sublingual therapy) had no evidence of illicit opiate use, compared with 64% of patients receiving usual sublingual buprenorphine therapy.237 In addition, 11 patients with buprenorphine implants required supplemental sublingual dosing but had no evidence of illicit opiate use; one of these patients required supplemental dosing only at the end of the implantation period, potentially indicating the need for early implant replacement.237

Two additional studies in patients who had not previously received buprenorphine therapy suggested that buprenorphine subdermal implants should not be used for patients who are new to buprenorphine treatment or who have not achieved and sustained prolonged clinical stability while receiving a low to moderate dosage of an oral transmucosal buprenorphine-containing preparation; the implant dosage appears to be too low to be effective in these populations.237

Other Uses

Buprenorphine has been used in a limited number of patients as an antagonist to reverse fentanyl-induced anesthesia† and provide subsequent analgesia;42,71,144 however, buprenorphine-induced reversal of fentanyl anesthesia may occur slowly, and usefulness of the drug in situations when rapid recovery from fentanyl anesthesia is desirable may therefore be limited.42

Buprenorphine has caused substantial clinical improvement in a limited number of patients with refractory endogenous depression† when administered as a sublingual tablet for several days.153,154,155

Administration

Risk Evaluation and Mitigation Strategies

FDA required and approved a REMS for oral transmucosal formulations of buprenorphine alone or in fixed combination with naloxone (buprenorphine/naloxone) that are used for treatment of opiate dependence (opiate use disorder), for opiate analgesics used in the outpatient setting (including buprenorphine transdermal systems and buprenorphine buccally dissolving strips), for buprenorphine subdermal implants, and for buprenorphine extended-release subcutaneous injection.215,216,227,238,239 (See REMS.)

The REMS program for buprenorphine-containing oral transmucosal preparations (i.e., sublingual tablets and sublingually or buccally dissolving strips) used for the treatment of opiate dependence include a medication guide requirement and outline steps to ensure documentation of safe use conditions and proper monitoring for each patient receiving the drug.227 The REMS requirement does not apply when buprenorphine-containing oral transmucosal preparations are dispensed to patients admitted to an opiate treatment program.227 The goals are to reduce the risk of accidental overdosage, misuse, and abuse and to inform prescribers, pharmacists, and patients of the serious risks associated with these preparations.227 Additional information about the REMS programs for buprenorphine-containing oral transmucosal preparations can be obtained at [Web].227

The Sublocade^® REMS program is intended to reduce the risk of serious harm or death that could result from IV self-administration by ensuring that buprenorphine extended-release subcutaneous injection is dispensed by certified health care settings and pharmacies directly to health care providers for administration by a health care professional.238 The REMS includes a redistricted distribution program.238 Additional information about the program can be obtained at [Web].238

The goals of the Probuphine^® REMS are to reduce the risks of complications of buprenorphine subdermal implant migration, protrusion, or expulsion; nerve damage associated with implant insertion and removal; and accidental overdosage, misuse, and abuse if an implant is expelled or protrudes from the skin.239 The program includes requirements for certification of pharmacies that dispense the implant, clinicians who prescribe the implant, and clinicians who insert the implants; monitoring and documentation of implant removal; restriction of distribution to settings with a certified prescriber; and a medication guide for patients.239 Additional information about the program can be obtained at [Web].239

FDA also has approved a REMS program for opiate analgesics used in the outpatient setting and not covered by other REMS programs, including buprenorphine transdermal system (Butrans^®) and buprenorphine buccally dissolving strips (Belbuca^®).215 The goals of this program are to reduce the occurrence of addiction, unintentional overdosage, and death resulting from inappropriate prescribing, misuse, and abuse of opiate analgesics.215 The program consists of educational programs for health professionals, a patient counseling guide, and a product-specific medication guide for patients.215 Additional information about the program can be obtained at [Web].215

In addition to the restricted distribution systems established for certain buprenorphine-containing preparations (extended-release subcutaneous injection, subdermal implants) under REMS programs, buprenorphine and buprenorphine/naloxone may be prescribed for the treatment of opiate dependence only by clinicians who meet certain requirements, have notified the Secretary of the US Department of Health and Human Services (HHS) of their intent to prescribe these preparations for this indication, and have been assigned a unique identification number that must be included on each prescription for the drug.202,214,229,233

Parenteral Administration

Conventional Injection for Pain Management

For the relief of pain severe enough to require opiate analgesia and for which alternative treatments are inadequate, buprenorphine hydrochloride is administered by IM or slow (over a period of at least 2 minutes) IV injection.1 The drug has also been administered by continuous IV infusion†,32,33,34 by IM103 or IV76,79 injection using a patient-controlled infusion device†, and by epidural injection†.23,24,25,26,28,29,30,31,50,78,92,192

For continuous IV infusion†, buprenorphine hydrochloride injection has been diluted to a concentration of 15 mcg/mL in 0.9% sodium chloride and administered via a controlled-infusion device.32 For continuous IV infusion†, the drug should be administered only by qualified individuals familiar with the technique and patient management problems (i.e., respiratory depression) associated with buprenorphine administration.33,34 For epidural injection†, buprenorphine hydrochloride injection has been diluted to a concentration of 6-30 mcg/mL in 0.9% sodium chloride.23,24,25,26,28,29,30,31,78,92,192

Buprenorphine hydrochloride injection and diluted solutions of the drug should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit.1

If accidental dermal exposure occurs, any contaminated clothing should be removed and the affected area rinsed with water.1

Extended-release Subcutaneous Injection for Opiate Dependence

For the management of opiate dependence in patients who have initiated buprenorphine therapy with an oral transmucosal buprenorphine-containing preparation followed by dosage adjustment for at least 7 days, buprenorphine extended-release injection is administered by subcutaneous injection into the abdomen at monthly intervals (minimum of 26 days between injections); this formulation is for subcutaneous injection only and should not be administered IV or IM.236 A clinician must prepare and administer the injection.236

Buprenorphine extended-release injection should be removed from the refrigerator and allowed to reach room temperature (over at least 15 minutes) prior to administration.236 Each injection should be administered using the manufacturer-provided syringe and safety needle.236 The foil pouch containing the syringe should not be opened until the patient has arrived for the injection, and the safety needle should not be attached until just prior to administration.236 The injection should be inspected visually for discoloration and particulate matter prior to administration; the injection should appear clear, viscous, and colorless to yellow to amber.236 The injection should be discarded if stored at room temperature for longer than 7 days.236 Injections should be made into the abdomen between the transpyloric and transtubercular planes at a site with adequate subcutaneous tissue that is free of skin conditions (e.g., nodules, lesions, excessive pigmentation).236 Injections should not be made into areas that are irritated, reddened, bruised, infected, or scarred.236 It is recommended that injections be made with the patient in the supine position.236 Injection sites should be rotated.236

Following administration, the injection forms a solid depot from which buprenorphine is gradually released.236 Patients should be advised that a lump may be present at the injection site for several weeks and that it will decrease in size over time.236,248 Patient should be instructed that they should not rub or massage the injection site or allow belts or waistbands to rub the site.236,248 Injection sites should be monitored for signs of infection and for evidence of tampering or attempted depot removal.236 A depot can be excised surgically, if necessary, under local anesthesia within 14 days of injection.236

Subdermal Implants for Opiate Dependence

For maintenance treatment of opiate dependence in patients who have achieved and maintained prolonged clinical stability on a low to moderate dosage of an oral transmucosal buprenorphine-containing preparation, buprenorphine hydrochloride implants are inserted subdermally in the inner aspect of the upper arm.237 Clinicians must successfully complete required training and become certified prior to prescribing buprenorphine implant therapy; those performing implant insertion or removal procedures must successfully complete training on these procedures and be certified to perform implant insertion.237,239 Patients must be monitored to ensure that buprenorphine implants are removed by a clinician with appropriate certification, and clinicians must maintain documentation of implant insertion and removal in each patient's medical record.237,239 A surgical specialist consulted to assist with a difficult implant removal does not require certification.237

Each buprenorphine dose consists of 4 implants that are intended to be left in place for 6 months and then removed by the end of the sixth month.237 If continued implant therapy is desired at the time the initial implants are removed, new implants may be inserted subdermally in the contralateral arm.237 After one insertion in each arm, most patients should be transitioned back to oral transmucosal buprenorphine therapy, since experience is lacking with insertion of implants into other sites in the arm or with insertion of new implants at prior administration sites.237 The manufacturer's prescribing information should be consulted for proper methods of implant insertion and removal and associated precautions.237 The presence of each implant should always be verified by palpation or, if necessary, by ultrasound or magnetic resonance imaging (MRI) immediately after insertion and prior to attempted removal.237

Proper implant placement is essential to avoid serious complications and to facilitate removal.237 The implant site should be examined one week following insertion for signs of infection, adequacy of wound healing, and evidence of implant extrusion.237 If an implant is expelled spontaneously, the expelled portion should be measured to ensure that it is intact; any partial implant remaining in the patient's arm should be removed, and the incision site should be examined for infection and to determine whether the remaining implants should be removed.237 A replacement for the expelled implant may be inserted in the same arm medially or laterally to the existing implants or, alternatively, in the contralateral arm.237

Sublingual Administration

Sublingual Preparations for Opiate Dependence

For management of opiate dependence, buprenorphine hydrochloride is administered sublingually as a single agent (as sublingual tablets) or in fixed combination with naloxone hydrochloride (as sublingual tablets and sublingually dissolving strips).202,214,233,235 Buprenorphine/naloxone sublingually dissolving strips (Suboxone^®) may be administered either sublingually or buccally during maintenance treatment of opiate dependence; however, sublingual administration of this formulation is recommended during induction therapy to minimize exposure to naloxone and reduce the risk of withdrawal.214

Buprenorphine or buprenorphine/naloxone sublingual tablets are placed under the tongue and allowed to dissolve.202,233,235 Drinking warm fluids prior to administration may aid dissolution.204 For doses requiring multiple tablets, patients are advised to place all the tablets under the tongue at once.202,233,235 Alternatively, patients may place 2 tablets under the tongue at a time if they are unable to place more than 2 tablets comfortably under the tongue.202,233 Patients should continue to hold the tablets under the tongue until the tablets dissolve.202,233,235 If sequential administration is preferred, patients should adhere to the same manner of dosing with continued use to ensure consistent bioavailability.235 The median dissolution time for buprenorphine/naloxone (Zubsolv^®) sublingual tablets is 5 minutes.235

Buprenorphine/naloxone sublingually dissolving strips are placed under the tongue, on either side near the base of the tongue.214 The strip(s) should be kept under the tongue until completely dissolved; drinking water prior to administration may aid dissolution.214 Up to 2 strips may be administered at one time and should be placed under opposite sides of the tongue in a way that minimizes overlapping.214 When more than 2 strips are required to complete the dose, additional strips may be administered after the first 2 strips have dissolved.214 Strips should not be moved after placement.214

To ensure consistency in bioavailability, patients should follow a consistent manner of administration.202,214,233,235 Proper administration technique should be demonstrated to the patient.202,214,233,235 The sublingual tablet or strip must be administered whole and should not be cut.202,214,233,235 Patients should not eat or drink until the tablet or strip is completely dissolved.202,214,233,235 Talking while the tablet or strip is dissolving, chewing the tablet or strip, or swallowing the tablet or strip may affect absorption and, therefore, efficacy of the drug and should be avoided.202,214,233,235 Patients should be advised to keep unused sublingual tablets or strips containing buprenorphine out of sight and reach of children.202,214,233,235 After completion of sublingual buprenorphine therapy, patients should be advised to discard any remaining tablets or strips by removing the tablets or strips from their packaging and then flushing them down the toilet.202,214,233,235

Buccal Administration

Buccal Preparations for Pain Management

For the relief of pain severe enough to require daily, around-the-clock, long-term opiate analgesia and for which alternative treatment options are inadequate, buprenorphine hydrochloride is administered buccally every 12 hours as buccally dissolving strips (Belbuca^®).232 The manufacturer states that this formulation is for buccal use only.232

Immediately prior to administering buprenorphine buccally dissolving strips (Belbuca^®), the patient must wet the inside of the cheek with the tongue or rinse the mouth with water to wet the area for placement.232 The strip is then applied immediately after removal from the individually sealed package with the yellow side of the strip placed against the inside of the cheek, where it will adhere to the moist mucosa.232 The entire strip should be held in place with clean, dry fingers for 5 seconds and then left in place until fully dissolved (usually within 30 minutes).232 The strip should not be applied to areas of the mouth with open sores or lesions.232 The strip should not be manipulated with the tongue or fingers; eating and drinking should be avoided until the strip has dissolved.232 Chewing or swallowing the strip may result in lower peak plasma concentrations and reduced bioavailability of the drug.232 The strip should not be used if the package seal is broken or the strip is cut, damaged, or altered in any way.232 Proper administration technique should be demonstrated to the patient.232

Patients should be advised to keep the strips out of sight and reach of children.232 Any strips that are no longer needed should be removed from their packaging and flushed down the toilet.232

Buccal Preparations for Opiate Dependence

For the management of opiate dependence, buprenorphine/naloxone is administered buccally as buccally dissolving strips (Bunavail^®).234 Sublingually dissolving strips containing buprenorphine/naloxone (Suboxone^®) may be administered either sublingually or buccally during maintenance treatment of opiate dependence; however, sublingual administration of this formulation is recommended during induction therapy to minimize exposure to naloxone and reduce the risk of withdrawal.214 To ensure consistency in bioavailability, patients should follow a consistent manner of administration.214

Immediately prior to administering buprenorphine/naloxone buccally dissolving strips (Bunavail^®), the patient should wet the inside of the cheek with the tongue or rinse the mouth with water to moisten the area for placement.234 The strip is then applied immediately after removal from the individually sealed package.234 The strip should be held by clean, dry fingers with the text on the strip facing up and then placed against the inside of the cheek with the text side against the cheek; the strip should be pressed in place for 5 seconds.234 If a second strip is required to complete the dose, it should be placed on the inside of the other cheek immediately after the first strip is administered.234 When multiple strips are required, no more than 2 strips should be applied to the inside of one cheek at a time.234 The strip should not be manipulated with the tongue or fingers; eating and drinking should be avoided until the strip has dissolved.234 The strip must be administered whole and should not be cut or torn.234 Chewing or swallowing the strip may alter absorption and should be avoided.234

For buccal administration of buprenorphine/naloxone sublingually dissolving strips (Suboxone^®), one strip is placed on the inside of the right or left cheek.214 If a second strip is required to complete the dose, it is placed on the inside of the opposite cheek.214 If a third strip is required, it is placed on the inside of the right or left cheek after the first 2 strips have dissolved.214 Strips should not be moved after placement and must be left in place on the inside of the cheek until completely dissolved.214 Eating and drinking should be avoided until the strip has completely dissolved.214 The strip must be administered whole and should not be cut.214 Talking while the strip is dissolving, chewing the strip, or swallowing the strip may affect absorption and, therefore, efficacy of the drug and should be avoided.214

Patients should be advised to keep the strips out of sight and reach of children.234 Any strips that are no longer needed should be removed from their packaging and flushed down the toilet.234

Transdermal Administration

Transdermal System for Pain Management

For the relief of pain severe enough to require daily, around-the-clock, long-term opiate analgesia and for which alternative treatment options are inadequate, buprenorphine is administered transdermally.213 Each buprenorphine transdermal system is intended to be worn continuously for 7 days; subsequent systems should be applied to a different site after removal of the previous system.213 The manufacturer recommends an interval of at least 21 days between applications to a particular site, since more frequent application at the same site may result in variable absorption.213 Rotation among 8 recommended application sites (4 on each side of the body) is advised.213

Patients receiving buprenorphine transdermal systems should be carefully instructed in the proper use and disposal of the transdermal system.213 The transdermal system should not be used if the seal of the package is broken or if the system is cut, damaged, or altered in any way.213 The transdermal system should be removed from the sealed pouch and the protective-liner covering should be peeled and discarded just prior to application of the system.213 The transdermal system should be applied to a dry, intact, nonirritated, hairless or nearly hairless surface on the upper chest, upper back, side of chest, or upper outer arm on either side of the body by firmly pressing the system by hand for 15 seconds with the adhesive side touching the skin and ensuring that contact is complete, particularly around the edges.213 If 2 systems are applied for a single dose, the systems should be applied adjacently at the same site and should always be applied and removed at the same time.213 If needed, hair at the application site should be clipped, not shaved, prior to application of the transdermal system.213 If the site must be cleansed prior to application, only water should be used.213 Soaps, oils, lotions, alcohol, or abrasive devices could alter the absorption of buprenorphine and should not be used.213

If a system should inadvertently come off during the period of use, a new system may be applied to a different skin site and left in place for 7 days.213 Patients who experience difficulty with system adhesion should be advised that they may tape the edges of the system in place with first-aid tape.213 If adhesion problems persist, patients may apply a transparent, waterproof or semipermeable adhesive film dressing that is suitable for 7 days of wear (e.g., Bioclusive^®, Tegaderm^®) over the system.213,221

Although incidental exposure to water (e..g., while showering or bathing) is acceptable, the transdermal system should not be exposed to external heat sources, hot water, or prolonged direct sunlight.213 Patients should be advised to avoid sunbathing, taking hot baths, or exposing the application site and surrounding area to direct external heat sources (e.g., heating pads, electric blankets, heat or tanning lamps, saunas, hot tubs, heated water beds) while wearing the transdermal system, since temperature-dependent increases in percutaneous absorption of buprenorphine from the system are possible under such conditions and may result in fatal overdosage.213

Patients should be advised to keep both used and unused buprenorphine transdermal systems out of the reach of children.213 The manufacturer states that immediately following removal, used systems should be properly discarded.213 In addition, following completion of a course of transdermal buprenorphine therapy, any unused systems should be removed from the package and properly discarded.213 Systems to be discarded should be folded carefully so that the adhesive side adheres to itself and then should be flushed down the toilet; transdermal systems may be disposed in the trash only after the system has been sealed in the manufacturer-supplied disposal unit.213 If the drug-containing adhesive matrix accidentally contacts the skin, the affected area should be washed with water; soap, alcohol, or other solvents should not be used to cleanse the area since they actually may enhance percutaneous absorption of buprenorphine.213 Patients or caregivers should always wash their hands after applying or handling a buprenorphine transdermal system.213

Dosage

Dosage of buprenorphine and buprenorphine hydrochloride usually is expressed in terms of buprenorphine.1 Dosage of buprenorphine hydrochloride subdermal implants may be expressed as either the salt or the base.237

Pain

Opiate analgesics should be given at the lowest effective dosage and for the shortest duration of therapy consistent with the treatment goals of the patient.1,213,232,411,413,431,432,435 Initial dosage of buprenorphine should be individualized according to severity of pain, response, prior analgesic use, and risk factors for addiction, abuse, and misuse.1,213,232 Appropriate dosage selection and titration are essential to reduce the risk of respiratory depression.1,213,232 Overestimation of the dosage of buprenorphine when transferring patients from other opiate therapy to buprenorphine therapy can result in fatal overdosage with the first dose.1,213,232 Patients should be monitored closely for respiratory depression, especially during the first 24-72 hours of therapy and following any increase in dosage, and dosage should be adjusted accordingly.1,213,232 If concomitant therapy with other CNS depressants is required, the lowest effective dosages and shortest possible duration of concomitant therapy should be used.1,213,232,700,703

For acute pain not related to trauma or surgery, the prescribed quantity should be limited to the amount needed for the expected duration of pain severe enough to require opiate analgesia (generally 3 days or less and rarely more than 7 days).411,433,434,435

When opiate analgesics are used for the management of chronic noncancer pain, the US Centers for Disease Control and Prevention (CDC) recommends that primary care clinicians carefully reassess individual benefits and risks before prescribing dosages equivalent to 50 mg or more of morphine sulfate daily and avoid dosages equivalent to 90 mg or more of morphine sulfate daily or carefully justify their decision to titrate the dosage to such levels.411 Other experts recommend consulting a pain management specialist before exceeding a dosage equivalent to 80-120 mg of morphine sulfate daily.423,431 Some states have set prescribing limits (e.g., maximum daily dosages that can be prescribed, dosage thresholds at which consultation with a specialist is mandated or recommended).411,420,421,423

Parenteral Dosage

For the relief of pain that is severe enough to require opiate analgesia and for which alternative treatments are inadequate, the usual IM or IV dosage of buprenorphine in patients 13 years of age and older is 0.3 mg given at intervals of up to every 6 hours as necessary.1 The initial dose (up to 0.3 mg) may be repeated once in 30-60 minutes, if needed.1 The dose should be limited to the minimum amount required in high-risk patients (e.g., geriatric or debilitated patients, those with respiratory disease) and in patients receiving other CNS depressants, including patients in the immediate postoperative period.1 Particular caution is necessary if the drug is administered IV, especially with initial doses.1 In some patients, it may be necessary to increase the dose up to 0.6 mg, but the manufacturer recommends that such relatively high doses only be administered IM and only to adults who are not considered high-risk patients.1 In some patients, a dosing interval greater than 6 hours may be adequate.71,72,97,99 Alternatively, a regimen including an initial dose of 0.3 mg of buprenorphine followed by another 0.3-mg dose repeated in 3 hours has been shown to be as effective as a single 0.6-mg dose in relieving postoperative pain.129 There are insufficient clinical data to recommend single doses greater than 0.6 mg for long-term use.1

Although children 2-12 years of age have received parenteral buprenorphine dosages of 2-6 mcg/kg every 4-6 hours, longer dosing intervals (e.g., every 6-8 hours) may be sufficient for some children, and a fixed around-the-clock dosing interval should not be used until an adequate dosing interval has been established by clinical observation of the patient.1 In addition, the manufacturer states that there are insufficient data in children 2-12 years of age to recommend buprenorphine doses exceeding 6 mcg/kg or administration of a repeat dose within 30-60 minutes of the initial dose.1

When buprenorphine has been administered by continuous IV infusion† in the management of postoperative pain,32,33,34 dosages of 25-250 mcg/hour have been used in adults.33,34

Buprenorphine has been administered epidurally† in the management of postoperative pain23,25,26,28,29,30,92 in single doses of 60 mcg, up to a mean total dose of 180 mcg administered over a 48-hour period.23 Buprenorphine has also been administered epidurally† in a dose of 0.3 mg as a supplement to surgical anesthesia with a local anesthetic.24,192 In the management of severe, chronic pain (e.g., in terminally ill patients), buprenorphine doses of 0.15-0.3 mg have been administered epidurally as frequently as every 6 hours up to a mean total daily dose of 0.86 mg (range: 0.15-7.2 mg).31

The manufacturer states that data are insufficient to recommend a parenteral buprenorphine dosage for infants younger than 2 years of age.1 In children 9 months to 9 years of age† undergoing circumcision, some clinicians have used an initial IM buprenorphine dose of 3 mcg/kg as an adjunct to surgical anesthesia followed by additional 3-mcg/kg doses as necessary to provide analgesia postoperatively.27

Transdermal Dosage

Buprenorphine transdermal system should be prescribed only by clinicians who are knowledgeable in the use of potent opiates for the management of chronic pain.213 Dosages of 7.5, 10, 15, and 20 mcg/hour should be reserved for patients who are opiate experienced (i.e., have been receiving oral morphine sulfate dosages of up to 80 mg or more daily [or equivalent] for one week or longer) and have developed tolerance to an opiate of comparable potency.213

In opiate-naive adults with pain that is severe enough to require daily, around-the-clock, long-term opiate analgesia and for which alternative treatments are inadequate, treatment with transdermal buprenorphine should be initiated at a dosage of 5 mcg/hour.213

When patients currently receiving opiate agonist therapy are switched to transdermal buprenorphine, there is a potential for buprenorphine to precipitate withdrawal.213 In these patients, the current opiate regimen should be tapered over a period of up to 7 days to a total 24-hour dosage equivalent to 30 mg or less of oral morphine sulfate.213 For patients whose prior total daily dosage of opiates was less than 30 mg of oral morphine sulfate (or equivalent), transdermal buprenorphine may be initiated at a dosage of 5 mcg/hour.213 For patients whose prior total daily dosage was 30-80 mg of oral morphine sulfate (or equivalent), transdermal buprenorphine may be initiated at a dosage of 10 mcg/hour.213 Patients may receive supplemental short-acting analgesics as needed until adequate analgesia is attained.213 For patients whose prior total daily dosage exceeded 80 mg of oral morphine sulfate (or equivalent), buprenorphine 20 mcg/hour may not provide adequate analgesia and an alternative analgesic should be considered.213 When therapy with a buprenorphine transdermal system is initiated, all other around-the-clock opiate analgesics should be discontinued.213 Buprenorphine may be initiated at the next dosing interval following discontinuance of the current opiate regimen.213 Particularly close monitoring is required when patients are switched from methadone, since conversion ratios between methadone and other opiates vary widely depending on extent of prior methadone exposure and because methadone has a long half-life and tends to accumulate in plasma.213

Buprenorphine dosage may be titrated upward at minimum intervals of 72 hours to a level that provides adequate analgesia and minimizes adverse effects.213 The maximum recommended transdermal dosage of buprenorphine is 20 mcg/hour, since higher dosages have been shown to prolong the QT interval.213 Dosage may be adjusted in increments of 5, 7.5, or 10 mcg/hour by simultaneously applying no more than two 5-, 7.5-, or 10-mcg/hour systems; the total combined dosage of the 2 transdermal systems should not exceed 20 mcg/hour.213

Patients should be reevaluated continually for adequacy of pain control and for adverse effects, as well as for the development of addiction, abuse, or misuse.213 Patients who experience episodes of breakthrough pain may require dosage adjustment or supplemental analgesia (i.e.,“ rescue” therapy with an immediate-release analgesic).213 If the level of pain increases after dosage stabilization, an attempt should be made to identify the source of increased pain before increasing the dosage.213 Frequent communication is important among the prescriber, other members of the healthcare team, the patient, and the patient's caregiver or family during periods of changing analgesic requirements, including the initial dosage titration period.213 During long-term therapy, the continued need for opiate analgesics should be periodically reevaluated.213 If unacceptable adverse effects are observed, dosage reduction should be considered.213

When the patient no longer requires buprenorphine therapy, the dosage should be tapered gradually every 7 days to prevent symptoms of opiate withdrawal.213 The use of an appropriate short-acting opiate may be considered during the tapering process.213 Therapy with buprenorphine transdermal system should not be discontinued abruptly.213

Buccal Dosage

Buprenorphine hydrochloride buccally dissolving strips (Belbuca^®) should be prescribed only by clinicians who are knowledgeable in the use of potent opiates for the management of chronic pain.232

For the management of pain that is severe enough to require daily, around-the-clock, long-term opiate analgesia and for which alternative treatments are inadequate, treatment with buprenorphine bucally dissolving strips should be initiated at a dosage of 75 mcg once daily or, if tolerated, 75 mcg every 12 hours in adults who are opiate-naive or are not tolerant to opiates.232 After at least 4 days at this initial dosage, dosage may be increased to 150 mcg every 12 hours.232 Use of higher initial dosages in patients who are not opiate tolerant may cause fatal respiratory depression.232

When patients currently receiving opiate agonist therapy are switched to intrabuccal buprenorphine, there is a potential for buprenorphine to precipitate withdrawal.232 In these patients, the current opiate regimen should be tapered to a total 24-hour dosage equivalent to 30 mg or less of oral morphine sulfate.232 For patients whose prior total daily dosage of opiates was less than 30 mg of oral morphine sulfate (or equivalent), intrabuccal buprenorphine may be initiated at a dosage of 75 mcg once daily or 75 mcg every 12 hours.232 For patients whose prior total daily dosage was 30-89 mg of oral morphine sulfate (or equivalent), intrabuccal buprenorphine may be initiated at a dosage of 150 mcg every 12 hours.232 For those whose prior total daily dosage was 90-160 mg of oral morphine sulfate (or equivalent), intrabuccal buprenorphine may be initiated at a dosage of 300 mcg every 12 hours.232 Patients may receive supplemental short-acting analgesics as needed until adequate analgesia is attained.232 For patients whose prior total daily dosage exceeded 160 mg of oral morphine sulfate (or equivalent), buprenorphine buccally dissolving strips may not provide adequate analgesia and an alternative analgesic should be considered.232 When therapy with buprenorphine buccally dissolving strips is initiated, all other around-the-clock opiate analgesics should be discontinued.232 Particularly close monitoring is required when patients are switched from methadone, since conversion ratios between methadone and other opiates vary widely depending on extent of prior methadone exposure and because methadone has a long half-life and tends to accumulate in plasma.232

Buprenorphine dosage may be titrated upward in increments of no more than 150 mcg every 12 hours at minimum intervals of 4 days to a level that provides adequate analgesia and minimizes adverse effects.232 Doses of 600, 750, and 900 mcg should be used only following titration from lower intrabuccal dosages.232 Dosages of up to 450 mcg every 12 hours were studied in opiate-naive patients in clinical trials.232 The maximum recommended intrabuccal dosage is 900 mcg every 12 hours because of the risk of QT-interval prolongation; if this dosage fails to provide adequate analgesia, an alternative analgesic should be considered.232

Patients should be reevaluated continually for adequacy of pain control and for adverse effects, as well as for the development of addiction, abuse, or misuse.232 Patients who experience episodes of breakthrough pain may require dosage adjustment or supplemental analgesia (i.e.,“ rescue” therapy with an immediate-release analgesic).232 If the level of pain increases after dosage stabilization, an attempt should be made to identify the source of increased pain before increasing the dosage.232 Frequent communication is important among the prescriber, other members of the healthcare team, the patient, and the patient's caregiver or family during periods of changing analgesic requirements, including the initial dosage titration period.232 During long-term therapy, the continued need for opiate analgesics should be periodically reevaluated.232 If unacceptable adverse effects are observed, dosage should be adjusted to obtain an appropriate balance between pain control and adverse effects.232

In patients with known or suspected mucositis, the usual initial dosage and each incremental dosage during titration should be reduced by one-half because of the potential for higher peak concentrations and systemic exposure to the drug.232

When the patient no longer requires buprenorphine therapy, the dosage should be tapered gradually to prevent symptoms of opiate withdrawal.232 Intrabuccal therapy with buprenorphine should not be discontinued abruptly.232 If manifestations of withdrawal occur, the dosage should be increased to the prior level and tapered more slowly by increasing the interval between dosage reductions and/or reducing the amount of each incremental change in dose.232

For further information on the management of opiate analgesic therapy, see Dosage and Administration: Dosage, in the Opiate Agonists General Statement 28:08.08.

Opiate Dependence

Buprenorphine and buprenorphine/naloxone are prescribed and distributed in the management of opiate dependence (opiate use disorder [OUD]) under a restricted distribution program.202,214,236,237

Oral transmucosal preparations containing buprenorphine or buprenorphine/naloxone may be used during induction and/or maintenance phases of treatment, while buprenorphine extended-release subcutaneous injection and buprenorphine subdermal implants are used only during maintenance.202,214,233,234,235,236,237,246 Because all oral transmucosal formulations are not bioequivalent, dosage recommendations vary according to differences in bioavailability.234,235,248 Recommended dosage ranges (based on the buprenorphine component) are the same for generic buprenorphine sublingual tablets (i.e., generic equivalents of Subutex^® sublingual tablets [branded formulation no longer commercially available in the US]), generic buprenorphine/naloxone sublingual tablets (i.e., generic equivalents of Suboxone^® sublingual tablets [branded formulation no longer commercially available in the US]), and buprenorphine/naloxone sublingually dissolving strips (Suboxone^®),248 although some strengths and dose combinations of these preparations are not bioequivalent.202,214 Dosage ranges for certain other oral transmucosal buprenorphine/naloxone preparations (i.e., Bunavail^® buccally dissolving strips, Zubsolv^® sublingual tablets) are lower, reflecting the greater bioavailability of these preparations.234,235,248 Although generic buprenorphine/naloxone sublingual tablets are labeled in the US only for maintenance treatment,202 this formulation also has been used (similarly to other oral transmucosal buprenorphine/naloxone preparations) in the induction† phase of treatment.227,246

Presence of naloxone, an opiate antagonist, in the fixed-combination preparation is intended to deter parenteral abuse of buprenorphine by individuals dependent on other opiates since a sufficient amount of the opiate antagonist is present in the formulation to precipitate opiate withdrawal if administered parenterally (but not sublingually).247 When administered sublingually, systemic naloxone concentrations are insufficient to elicit clinically important effects; in addition, sublingual administration of buprenorphine and buprenorphine/naloxone has been shown to elicit similar clinical, physiologic, and subjective effects.214

Although buprenorphine traditionally has been considered the preferred drug for the initial (i.e., induction) phase of treatment,233,250 additional experience indicates that either buprenorphine or buprenorphine/naloxone may be used for induction in patients dependent on heroin or other short-acting opiates.214,234,235,247,250 Use of buprenorphine/naloxone for the induction phase of treatment in patients dependent on long-acting opiates has not been evaluated to date in adequate and well-controlled studies;214,234,235 the manufacturers and some experts still recommend use of buprenorphine alone for induction in these patients.214,234,235,247,259 Following induction, buprenorphine/naloxone is the preferred drug for maintenance treatment when use includes unsupervised administration.233 Administration of buprenorphine without naloxone in an unsupervised setting should be limited to pregnant women and patients who cannot tolerate naloxone.202,233,247,254,256

Prior to induction, the type of opiate dependence (i.e., long- or short-acting opiate), time since last opiate use, and degree of opiate dependence should be considered.214,233,234,235 Abuse of long-acting formulations by manipulation of the dosage form (e.g., crushing and snorting or injecting extended-release oral dosage forms) may cause these formulations to act as short-acting drugs.249,250 To avoid precipitating withdrawal, the first dose of buprenorphine or buprenorphine/naloxone should be given when objective and clear signs of opiate withdrawal are evident.214,233,234,235,247,250

In individuals dependent on heroin or other short-acting opiates, the manufacturers state that the first dose of buprenorphine or buprenorphine/naloxone should be administered at least 4 or 6 hours, respectively, after the last use of the opiate.214,233,234,235 Some experts recommend waiting at least 6-12 hours after last use of short-acting opiates and recommend use of an opiate withdrawal scale (e.g., Clinical Opioid Withdrawal Scale [COWS] score of approximately 11-12 or higher) to establish that withdrawal is sufficient to allow for safe and comfortable induction.247,248,249,250 Administration of a low initial dose of buprenorphine or buprenorphine/naloxone also reduces the risk of precipitated withdrawal.247 Because gradual titration of buprenorphine dosage over several days has been associated with a high dropout rate during the induction phase in clinical studies, an adequate treatment dosage, titrated to clinical effectiveness, should be achieved as rapidly as possible once it has been established that the initial dose of the drug was well tolerated.214,233,234,235,247

Patients dependent on methadone or other long-acting opiates may be more susceptible than those who are dependent on short-acting opiates to precipitated and prolonged withdrawal during induction.214,233,234,235 Therefore, the first dose of buprenorphine should be given when objective and clear signs of opiate withdrawal are evident, generally not less than 24 hours after the last use of the opiate.233,247,248 Controlled experience with the transfer of patients from methadone maintenance to buprenorphine is limited.233 Withdrawal symptoms appear to be more likely in those receiving higher dosages of methadone hydrochloride (greater than 30 mg daily) and when the first dose of buprenorphine is given shortly after the last methadone dose.233 Thus, dosage of methadone hydrochloride should be tapered to approximately 30-40 mg daily or less and maintained at this level for at least a week prior to induction.248,249,250 Experts state that the first dose of buprenorphine may be administered at least 24-72 hours or longer after last use of long-acting opiates such as methadone and recommend use of an opiate withdrawal scale (e.g., COWS score of approximately 11-12 or higher) to establish that withdrawal is sufficient to allow for safe and comfortable induction.247,248,249,250

Induction in the prescribing clinician's office is recommended to reduce the risk of precipitated withdrawal;214,247 unsupervised administration may then be initiated as the patient's clinical stability allows.214 Although large, randomized, controlled studies are lacking, experts state that at-home induction (with early in-office follow-up) by patients dependent on short-acting opiates may be considered depending on the patient's circumstances if the patient and/or clinician is experienced with the use of buprenorphine and the patient can rate withdrawal symptoms, fully understand induction dosing instructions, and can and will contact the clinician as needed.247,248,250

Patients receiving maintenance treatment should be seen at reasonable intervals (e.g., at least weekly during the first months of therapy) based on the individual's circumstances; once patients are receiving a stable buprenorphine dosage and are progressing toward treatment goals, less frequent (e.g., monthly) visits may be reasonable.214,247 Prescription quantities for unsupervised administration should take into account the patient's clinical stability, home situation, and ability to manage take-home medication.214 Authorization of multiple refills is not advised early in treatment or without appropriate follow-up visits.214 Review of state prescription drug monitoring program (PDMP) data for other prescribed drugs of concern, urine drug testing, and recall visits for “pill” counts also are recommended.247 If treatment goals are not being achieved, the appropriateness of the current therapy should be reevaluated.214 Unstable patients (e.g., those who are abusing or are dependent on various drugs or are unresponsive to psychosocial interventions) may require referral for more intensive treatment.214

For the maintenance treatment of opiate dependence, oral transmucosal preparations of buprenorphine/naloxone are labeled only for once-daily administration; however, other dosage regimens (i.e., administration every other day† or 3 times weekly† at a dose higher than the individually titrated daily dose) have been used once satisfactory stabilization has been achieved.246,248

Dosage of Lower-bioavailability Oral Transmucosal Formulations for Induction and Maintenance

When generic buprenorphine sublingual tablets (i.e., generic equivalents of Subutex^® sublingual tablets), generic buprenorphine/naloxone sublingual tablets (i.e., generic equivalents of Suboxone^® sublingual tablets), or buprenorphine/naloxone sublingually dissolving strips (Suboxone^®) are used for induction therapy, the recommended induction dosage of buprenorphine on day 1 is up to 8 mg (alone or in fixed combination with up to 2 mg of naloxone).214,233,248 Induction should be initiated on day 1 with a buprenorphine dose of 2 or 4 mg (alone or in fixed combination with naloxone 0.5 or 1 mg, respectively), with additional doses of 2 or 4 mg administered at approximately 2-hour intervals if there are continued withdrawal symptoms and sedation is not observed.214,233,246,247,248 Use of an opiate withdrawal scale (e.g., COWS) during induction can be helpful in assessing the effects of administered doses.247 On day 2, a single dose of up to 16 mg of buprenorphine (alone or in fixed combination with up to 4 mg of naloxone) is given.214,233,248 Other induction dosages that also employ a low initial dose with rapid titration to an effective maintenance dosage have been used.250

For oral transmucosal maintenance treatment, buprenorphine/naloxone is preferred over buprenorphine alone.233 (See initial paragraphs of Opiate Dependence under Dosage and Administration: Dosage.) From day 3 onward, buprenorphine/naloxone dosage should be adjusted in increments or decrements of 2 or 4 mg of buprenorphine in fixed combination with 0.5 or 1 mg, respectively, of naloxone daily to a dosage that suppresses opiate withdrawal symptoms and ensures that the patient continues buprenorphine treatment.202,214 The maintenance buprenorphine/naloxone dosage generally ranges from 4-24 mg of buprenorphine in fixed combination with 1-6 mg of naloxone daily.202,214 The recommended buprenorphine/naloxone target dosage during maintenance treatment is 16 mg of buprenorphine and 4 mg of naloxone as a single daily dose.202,214 Dosages exceeding 24 mg of buprenorphine in fixed combination with 6 mg of naloxone daily have not been shown to provide any additional clinical advantage.202,214

Zubsolv® Dosage for Induction and Maintenance

When Zubsolv^® sublingual tablets are used for induction and maintenance treatment, the recommended induction dosage on day 1 is up to 5.7 mg of buprenorphine in fixed combination with up to 1.4 mg of naloxone.235 Induction should be initiated with a buprenorphine/naloxone dose of 1.4 mg of buprenorphine in fixed combination with 0.36 mg of naloxone, with the remainder of the day 1 dosage (up to 4.2 mg of buprenorphine and up to 1.08 mg of naloxone) administered in divided doses as 1 or 2 tablets containing buprenorphine 1.4 mg and naloxone 0.36 mg at intervals of 1.5-2 hours.235 Some patients (e.g., those who recently received buprenorphine) may tolerate up to 3 tablets containing buprenorphine 1.4 mg and naloxone 0.36 mg as a single second dose.235 On day 2, a single dose of up to 11.4 mg of buprenorphine and 2.9 mg of naloxone is recommended.235

From day 3 onward, buprenorphine/naloxone dosage should be adjusted in increments or decrements of no more than 2.9 mg of buprenorphine and 0.71 mg of naloxone to a level that suppresses opiate withdrawal symptoms and ensures that the patient continues buprenorphine treatment.235 After induction and stabilization, the maintenance buprenorphine/naloxone dosage generally ranges from 2.9-17.2 mg of buprenorphine in fixed combination with 0.71-4.2 mg of naloxone daily.235 The recommended buprenorphine/naloxone target dosage during maintenance treatment is 11.4 mg of buprenorphine and 2.9 mg of naloxone as a single daily dose.235 Dosages exceeding 17.2 mg of buprenorphine in fixed combination with 4.2 mg of naloxone daily have not been shown to provide any additional clinical advantage.235

Bunavail® Dosage for Induction and Maintenance

When Bunavail^® buccally dissolving strips are used for induction and maintenance treatment, the recommended induction dosage on day 1 is up to 4.2 mg of buprenorphine in fixed combination with up to 0.7 mg of naloxone.234 Induction should be initiated with a buprenorphine/naloxone dose of 2.1 mg of buprenorphine in fixed combination with 0.3 mg of naloxone; a second dose of the same strength is administered approximately 2 hours later based on control of acute withdrawal symptoms.234 On Day 2, a single dose of up to 8.4 mg of buprenorphine in fixed combination with 1.4 mg of naloxone is recommended.234

From day 3 onward, buprenorphine/naloxone dosage should be adjusted in increments or decrements of 2.1 mg of buprenorphine and 0.3 mg of naloxone to a level that suppresses opiate withdrawal symptoms and ensures that the patient continues buprenorphine treatment.234 After induction and stabilization, the maintenance buprenorphine/naloxone dosage generally ranges from 2.1-12.6 mg of buprenorphine in fixed combination with 0.3-2.1 mg of naloxone daily.234 The recommended buprenorphine/naloxone target dosage during maintenance treatment is 8.4 mg of buprenorphine and 1.4 mg of naloxone as a single daily dose.234 Dosages exceeding 12.6 mg of buprenorphine in fixed combination with 2.1 mg of naloxone daily have not been shown to provide any additional clinical advantage.234

Dosage Adjustments When Switching Between Oral Transmucosal Strengths and Preparations

Not all formulations, strengths, or dose combinations of oral transmucosal buprenorphine/naloxone preparations are bioequivalent.202,214,234,235

Patients who currently are receiving generic buprenorphine or buprenorphine/naloxone sublingual tablets (i.e., generic equivalents of Subutex^® or Suboxone^® sublingual tablets) and are switching to buprenorphine/naloxone sublingually dissolving strips (Suboxone^®), or vice versa, should continue to receive the same drug dosage.202,214 However, not all strengths and dose combinations of the strips and sublingual tablets are bioequivalent.202,214 Because of potentially greater bioavailability with the strips relative to the tablets, patients should be monitored for underdosage (e.g., manifestations of withdrawal) or overdosage when switching between sublingual dosage forms and the dosage should be adjusted when indicated.202,214

The 4 strengths of Suboxone^® sublingually dissolving strips differ in size and buprenorphine and naloxone concentrations (on a % [w/w] basis).214 Switching between various combinations of lower- and higher-strength strips to obtain the same total dose may result in changes in systemic exposure to buprenorphine and naloxone and require that the patient be monitored for underdosage or overdosage.214 Therefore, substitution of one or more strip strengths for another without the prescriber's approval is not recommended.214 Because systemic exposure to naloxone is somewhat higher after buccal compared with sublingual administration of the strips, sublingual administration is recommended during induction to minimize the risk of precipitated withdrawal.214 However, exposure to buprenorphine is similar following either buccal or sublingual administration, and once induction is complete, patients can switch between buccal and sublingual administration without substantial risk of underdosage or overdosage.214

Bunavail^® and Zubsolv^® have different bioavailabilities than Suboxone^® (or generic equivalent) sublingual tablets.234,235 Patients switching between these preparations should receive a different dosage strength (see Table 1 and Table 2) and should be monitored for underdosage or overdosage.234,235 Dosage adjustments may be necessary.234,235 Systemic buprenorphine exposure following administration of one Suboxone^® sublingual tablet containing buprenorphine 8 mg and naloxone 2 mg is equivalent to that achieved following administration of one Bunavail^® buccally dissolving strip containing buprenorphine 4.2 mg and naloxone 0.7 mg or one Zubsolv^® sublingual tablet containing buprenorphine 5.7 mg and naloxone 1.4 mg.234,235

Extended-release Subcutaneous Injection Dosage for Maintenance Treatment

Maintenance treatment with buprenorphine extended-release subcutaneous injection may be initiated in patients who have initiated buprenorphine induction therapy with an oral transmucosal buprenorphine-containing preparation followed by dosage adjustment over a least 7 days to an oral transmucosal buprenorphine dosage of 8-24 mg daily (as Subutex^® or Suboxone^® [or equivalent generic buprenorphine or buprenorphine/naloxone preparation]) or a dosage of another oral transmucosal preparation that provides equivalent buprenorphine exposure.236 One Bunavail^® buccally dissolving strip containing buprenorphine 4.2 mg and naloxone 0.7 mg or one Zubsolv^® sublingual tablet containing buprenorphine 5.7 mg and naloxone 1.4 mg provides equivalent buprenorphine exposure as one Suboxone^® sublingual tablet containing buprenorphine 8 mg and naloxone 2 mg or one Subutex^® sublingual tablet containing buprenorphine 8 mg.236

The recommended dosage of buprenorphine extended-release subcutaneous injection following induction and dosage adjustment with oral transmucosal buprenorphine is 300 mg monthly for the first 2 months followed by a maintenance dosage of 100 mg monthly.236 The maintenance dosage may be increased to 300 mg monthly in patients who tolerate the 100-mg monthly dosage but do not achieve a satisfactory clinical response, as evidenced by self-reports or urine drug test results indicating illicit opiate use.236 If a dose is missed, the dose should be administered as soon as possible, with the following dose given no less than 26 days later.236 Occasional delays in dosing of up to 2 weeks are not expected to substantially alter the treatment effect.236 If a subcutaneous depot of the drug must be surgically excised, the patient should be monitored for manifestations of withdrawal and appropriate treatment (e.g., an oral transmucosal preparation of the drug) should be instituted as clinically indicated.236

Implant Dosage for Maintenance Treatment

Maintenance treatment with buprenorphine subdermal implants may be initiated in patients who have achieved and maintained prolonged clinical stability on oral transmucosal buprenorphine therapy; are currently receiving an oral transmucosal buprenorphine maintenance dosage of 8 mg daily or less (as Subutex^® or Suboxone^® [or equivalent generic buprenorphine or buprenorphine/naloxone preparation] or a dosage of another oral transmucosal preparation that provides comparable blood buprenorphine concentrations [e.g., Bunavail^® buccally dissolving strips at a dosage of buprenorphine 4.2 mg and naloxone 0.7 mg daily or less, Zubsolv^® sublingual tablets at a dosage of buprenorphine 5.7 mg and naloxone 1.4 mg daily or less]); and have received a stable oral transmucosal buprenorphine maintenance dosage of 8 mg daily or less for at least 3 months without the need for supplemental doses of the drug or dosage adjustments.237 The dosage of oral transmucosal buprenorphine should not be tapered to this dosage level solely for the purpose of transitioning to implant therapy.237 The 8-mg oral transmucosal dosage provides blood buprenorphine concentrations that are similar to or less than those provided by the recommended implant dosage.237

Each buprenorphine dose consists of 4 implants (each containing 80 mg of buprenorphine hydrochloride [equivalent to 74.2 mg of the base]) inserted subdermally in the inner aspect of the upper arm; the implants are intended to be left in place for 6 months and then removed by the end of the sixth month.237 If continued implant therapy is desired at the time the initial implants are removed, new implants may be inserted subdermally in the contralateral arm.237 If new implants are not inserted on the same day that the current ones are removed, patients should receive their previous dosage of oral transmucosal buprenorphine (i.e., the dosage they received prior to initiation of implant therapy) prior to additional implant therapy.237 After one insertion in each arm, most patients should be transitioned back to oral transmucosal buprenorphine therapy, since experience is lacking with insertion of implants at other sites in the arm or with insertion of new implants at prior administration sites (where potential effects of scarring and fibrosis on efficacy and safety are unknown).237

Although some patients may require occasional supplemental dosing with buprenorphine, the manufacturer states that patients should not be provided with prescriptions for oral transmucosal buprenorphine-containing preparations for use on as-needed basis.237 Instead, patients who feel the need for supplemental dosing should be evaluated promptly by a clinician.237 An ongoing need for supplemental dosing indicates that the amount of buprenorphine delivered by the implants is not adequate for stable maintenance treatment; use of an alternative buprenorphine preparation for maintenance treatment should be considered.237 If an implant is expelled spontaneously, the patient should be carefully monitored until the implant is replaced for withdrawal manifestations or other indications that supplemental oral transmucosal dosing may be required.237

Discontinuance

The decision to discontinue therapy with buprenorphine or buprenorphine/naloxone after a period of maintenance or brief stabilization should be made as part of a comprehensive treatment plan.202,214,233 Oral transmucosal dosage should be tapered to reduce the occurrence of withdrawal manifestations.202,214,233,234,235 Dosage generally is tapered over several months with close monitoring and a plan for sustaining recovery.247,248

If therapy with buprenorphine extended-release subcutaneous injection is discontinued, the patient should be monitored for several months for manifestations of withdrawal, since the onset of any withdrawal manifestations may be delayed; if treatment of withdrawal manifestations is required, use of oral transmucosal buprenorphine should be considered.236 In clinical trials, withdrawal manifestations were not observed during the first month following discontinuance of treatment with buprenorphine extended-release subcutaneous injection.236 Plasma concentrations of buprenorphine may be detectable for 12 months or longer if therapy with this formulation is discontinued after steady state has been achieved (4-6 months of treatment); the correlation between plasma and detectable urine concentrations of buprenorphine is not known.236

If therapy with buprenorphine implants is discontinued, the patient should be monitored for manifestations of withdrawal and use of a tapering dosage of oral transmucosal buprenorphine should be considered.237

Other Uses

To reverse fentanyl-induced anesthesia† and provide subsequent analgesia in adults, IV or IM buprenorphine doses of 0.3-0.8 mg have been administered 1-4 hours following induction of anesthesia and about 30 minutes prior to the end of surgery.42,71,144

Restricted Distribution Program for Buprenorphine Treatment of Opiate Dependence

The Drug Addiction Treatment Act of 2000 (DATA 2000) allows qualifying physicians to prescribe and dispense narcotics in schedules III, IV, and V of the Federal Controlled Substances Act that have been approved by FDA for detoxification or maintenance treatment of opiate dependence.205 The Comprehensive Addiction and Recovery Act of 2016 (CARA 2016) expands the categories of practitioners through October 1, 2021, to include qualifying nurse practitioners and physician assistants.229 Prior to passage of DATA 2000, opiate dependence treatment could be provided only at specially registered clinics.203 Under DATA 2000 and CARA 2016, prescription use of buprenorphine and buprenorphine/naloxone in the treatment of opiate dependence is limited to practitioners who meet certain requirements, have notified the Secretary of the US Department of Health and Human Services (HHS) of their intent to prescribe these preparations for this indication, and have been assigned a unique identification number that must be included on each prescription for the drug.202,214,229

Prescribers

DATA 2000 limited office-based use of buprenorphine and buprenorphine/naloxone for the management of opiate dependence to physicians who meet special training criteria and can provide appropriate services.226 CARA 2016 expanded the categories of practitioners to include qualifying nurse practitioners and physician assistants.229 To qualify, physicians must meet one or more of the following training requirements: hold a subspecialty board certification in addiction psychiatry from the American Board of Medical Specialties; hold subspecialty board certification in addiction medicine from the American Osteopathic Association; hold an addiction certification from the American Society of Addiction Medicine; have completed not less than 8 hours of authorized training on the management or treatment of opiate-dependent patients; have participated as an investigator in one or more clinical trials leading to the approval of a schedule III, IV, or V opiate for maintenance or detoxification treatment; and/or have other training or experience that is deemed by HHS or the state medical licensing board to demonstrate the physician's ability to treat and manage opiate-dependent patients.226 To quality, nurse practitioners and physician assistants must meet all of the following requirements: be authorized under state law to prescribe schedule III, IV, or V drugs for pain management; work in collaboration with or be supervised by a qualifying physician if so required by state law; and have completed not less than 24 hours of authorized initial training.229 In addition, practitioners must have the capacity to provide or to refer patients for needed ancillary services (i.e., psychosocial therapy) and must agree to prescribe schedule III, IV, or V drugs for management of opiate dependence for a limited number of patients.207,211,226,230 Before prescribing buprenorphine or buprenorphine/naloxone, practitioners who meet these criteria must notify the HHS Substance Abuse and Mental Health Services Administration (SAMHSA) of their intention to prescribe these agents.226

Initially, each qualifying practitioner, whether practicing individually or in a group practice, can treat no more than 30 patients at one time.211,222,230 Practitioners who have been certified to treat opiate dependence with buprenorphine for at least 1 year can apply to treat up to 100 patients at one time.222,230 Those who have been eligible to treat up to 100 patients at a time for at least one year without interruption can apply to increase the limit to 275 patients if they have additional credentialing or practice in a qualified setting.230,231 In addition, practitioners who currently are eligible to treat up to 100 patients but who otherwise are not eligible to increase their patient limit to 275 may request a temporary increase in certain emergency situations.230,231

The US Drug Enforcement Administration (DEA) will issue qualifying practitioners a unique identification number; this number indicates that the practitioner is qualified under DATA 2000 or CARA 2016 to prescribe buprenorphine for the management of opiate dependence and is intended to preserve the confidentiality of the patient.205,226 The SAMHSA Center for Substance Abuse Treatment will inform the practitioner of the new DEA identification number in writing via email.226 The DEA requires inclusion of the new identification number along with the practitioner's usual DEA number on all prescriptions issued for the treatment of opiate dependence.217,226 Although it is anticipated that most prescribers will obtain DEA identification numbers before prescribing buprenorphine or buprenorphine/naloxone for such use, DATA 2000 allows practitioners with qualifying credentials and/or training to write prescriptions for these agents before the DEA identification number is issued if the practitioner has notified SAMHSA of their intention to begin treating a patient immediately and has verified that SAMHSA received the notification form.226,227 Immediate treatment is limited to one patient per notification form, and no more than one form may be submitted on a given day.226

Practitioners should be aware that there are special federal regulations concerning confidentiality of substance abuse treatment records and the privacy of health records.228 Any patient-identifying information pertaining to treatment of substance abuse must be handled with a greater degree of confidentiality than patients' general medical information.227,228 Before a prescriber can disclose any information to a third party about a patient's treatment for substance abuse, that prescriber must obtain the patient's signed consent.227 Each disclosure made with the patient's consent must be accompanied by a statement indicating that unauthorized disclosure is prohibited.228

Dispensing Pharmacies

Each time a pharmacist fills a prescription for buprenorphine or buprenorphine/naloxone, the pharmacist is expected to verify that the prescription is from a prescriber who is in compliance with the provisions of DATA 2000.226 Practitioners who are qualified to prescribe buprenorphine and buprenorphine/naloxone and are in compliance with DATA 2000 are issued a unique DEA identification number; the new identification number along with the practitioner's usual DEA number is required on all prescriptions issued for the treatment of opiate dependence.203,217,226 If a prescription is phoned to the pharmacy, pharmacists must ensure that both numbers are on the prescription record.226 Pharmacists may utilize SAMHSA's online look-up tool (at [Web]) or contact 866-287-2728 to verify whether a prescriber is in compliance with the provisions of DATA 2000.226,227

If a pharmacist receives a prescription for buprenorphine or buprenorphine/naloxone that does not include the unique DEA identification number, the pharmacist should contact the prescriber for clarification and to confirm that the prescriber has notified SAMHSA of their intention to prescribe the drug.227 Pharmacists also may contact SAMHSA (at infobuprenorphine@samhsa.hhs.gov or 866-287-2728).226,227 It is anticipated that most prescribers will obtain DEA identification numbers before prescribing buprenorphine or buprenorphine/naloxone.227 However, DATA 2000 allows practitioners with qualifying credentials and/or training to write prescriptions for these agents before the DEA identification number is issued if the practitioner has notified SAMHSA of their intention to begin treating a patient immediately.227

Pharmacists should be aware that there are special federal regulations concerning confidentiality of substance abuse treatment records and the privacy of health records.228 Any patient-identifying information pertaining to treatment of substance abuse must be handled with a greater degree of confidentiality than patients' general medical information.227,228 Before a prescriber can disclose any information to a third party about a patient's treatment for substance abuse, the prescriber must obtain the patient's signed consent.227 When a prescriber directly transmits a prescription for a buprenorphine-containing preparation for treatment of substance abuse to a pharmacy, the patient's signed consent must be obtained before any patient-identifying information is further disclosed by the pharmacy.227

With the availability of buprenorphine for outpatient management of opiate dependence, many pharmacists have the opportunity to provide services that focus on ensuring appropriate drug administration, monitoring for adverse effects, alleviating withdrawal symptoms, treating intercurrent illnesses, minimizing diversion, and aiding in the prevention of relapse.204

A potential problem with take-home outpatient opiate agonist treatment is diversion.204,205 While the addition of naloxone is intended to decrease the potential for parenteral abuse of the combination preparations, the possibility of diversion exists because the drug may be used by opiate-dependent individuals in an attempt to attenuate withdrawal symptoms when illicit substances (e.g., heroin) are not available.204 In addition, individuals who are not opiate dependent may acquire buprenorphine for the purpose of getting high.205 To address diversion, patients may be asked on a random, unannounced basis to return to the clinic or pharmacy for verification of tablet counts.204 Since diversion is a concern, pharmacists should be alert for signs of this activity, including presentation of simultaneous prescriptions for the same patient from multiple prescribers, requests for additional doses or refills prior to the appropriate date, calls from opiate-dependent individuals who are not patients, and accidental loss or destruction of the drug.204,205 It is important to report any suspicion of diversion to the appropriate authorities.204

Dosage in Hepatic Impairment

Transdermal buprenorphine has not been studied in patients with severe hepatic impairment; use of an alternative analgesic regimen that allows for greater dosage flexibility should be considered in these patients.213

When buprenorphine buccally dissolving strips (Belbuca^®) are used for analgesia in patients with severe hepatic impairment (i.e., Child-Pugh class C), the usual initial dosage should be reduced and each incremental change in dosage during titration should be reduced by one-half (i.e., from 150 mcg to 75 mcg).232 No dosage adjustment is required in patients with moderate hepatic impairment, but patients with either moderate or severe hepatic impairment should be monitored for overdosage and toxicity.232

When buprenorphine or buprenorphine/naloxone is used sublingually or buccally for the management of opiate dependence in patients with mild hepatic impairment, plasma concentrations and half-lives of the drugs are not substantially altered.202,214,233,234,235 However, in individuals with moderate or severe hepatic impairment, plasma concentrations of both buprenorphine and naloxone are increased and half-lives of the drugs are prolonged.202,214,233,234,235 Naloxone is affected to a greater degree than buprenorphine, and the magnitude of the difference in effect is greater in individuals with severe hepatic impairment than in those with moderate hepatic impairment.202,214,234,235 (See Pharmacokinetics: Elimination.) This may result in an increased risk of precipitated withdrawal during induction and interference with buprenorphine's efficacy throughout treatment.202,214,234,235 Buprenorphine/naloxone should be avoided in patients with severe hepatic impairment and may not be appropriate for those with moderate hepatic impairment.202,214,234,235 In patients with moderate hepatic impairment, buprenorphine/naloxone is not recommended for induction therapy but may be used with caution and careful monitoring for maintenance treatment following induction therapy with buprenorphine alone.202,214,234,235 The manufacturer states that the initial dose and titration increments of buprenorphine administered as the single-entity sublingual tablets should be reduced by one-half in patients with severe hepatic impairment and recommends that patients with either moderate or severe hepatic impairment be monitored for buprenorphine overdosage or toxicity.233

Use of buprenorphine extended-release subcutaneous injection or buprenorphine subdermal implants is not recommended in patients with preexisting moderate to severe hepatic impairment since the extended-release injection does not allow for rapid adjustment of plasma buprenorphine concentrations and the implant dosage cannot be titrated.236,237

Adverse effects of buprenorphine are qualitatively similar to those of morphine,21,39,43,44,45,47,53,60,71,72,75,77,111,185 meperidine,68,69,71,80,184 and the opiate partial agonists (e.g., pentazocine, nalbuphine);40,57,79 however, the frequency of specific adverse effects produced by buprenorphine may differ from that of the various opiate agonists44,63,72,98,99,177,184,185 and partial agonists.40,71,177 Certain adverse effects of buprenorphine, including nausea, vomiting, CNS effects, and respiratory depression, appear to be dose and plasma concentration related.1,40,62,71,89 In opiate-tolerant patients, this relationship may be altered by the development of tolerance to opiate-related adverse effects; however, tolerance to opiate effects does not develop uniformly.1

When administered sublingually, the adverse effect profile of buprenorphine is similar to that of buprenorphine in fixed combination with naloxone (buprenorphine/naloxone).202 Sublingually dissolving strips and sublingual tablets containing buprenorphine/naloxone generally have similar adverse effect profiles.214 Following buccal administration of buprenorphine/naloxone sublingually dissolving strips, the adverse effect profile is similar to that observed following sublingual administration.214

Nervous System Effects

Buprenorphine may cause CNS depression, including somnolence, dizziness, alterations in judgment, and alterations in levels of consciousness, including coma.1,202,213,214

Sedation (e.g., drowsiness)1,9,40,44,48,51,53,65,67,69,71,72,75,79,83,95,96,98,110,183,184,185 is the most common adverse effect of parenteral buprenorphine, occurring in approximately two-thirds of patients;1 however, patients reportedly are easily aroused to an alert state.1,71,83,110 Dizziness1,9,44,71,79,99,183,185 and vertigo1 have been reported in about 5-10% of patients receiving parenteral buprenorphine.1 Headache1,9,57,71,107,183,185 has been reported in about 1-5% of these patients.1 Confusion,1,44,71,81,83,95 euphoria,1,44,71,93,95,102,107,111 weakness,1,183 fatigue,1,92 nervousness,1,107 mental depression,1,90,95 slurred speech,1 paresthesia,1 dreaming,1,183 psychosis,1 malaise,1 hallucinations,1,83,93 depersonalization,1,183 and coma1 have been reported in less than 1% of patients receiving parenteral buprenorphine for pain relief.1 Lightheadedness,56,88,93,95,183 insomnia,107 and disorientation183 have also occurred. Seizures,1 muscle twitching,107,183 lack of muscle coordination,1 ataxia,1 dysphoria,1,93 and agitation1,57,183 have been reported rarely.1 Psychotomimetic effects occur less frequently in patients receiving buprenorphine than in patients receiving pentazocine40 but more frequently than in patients receiving morphine.47

Buprenorphine has the potential to lower the seizure threshold and may aggravate seizure disorders and induce seizures in some clinical settings.213

Frequent adverse CNS effects reported in clinical trials in patients receiving transdermal buprenorphine include headache213,223 and dizziness213,223 (each occurring in about 5-15% of patients) and somnolence213,223 (occurring in up to 15% of patients).213 Fatigue,213 asthenia,213 insomnia,213 hypoesthesia,213 paresthesia,213 tremor,213 migraine,213 anxiety,213 and depression213 have been reported in about 1-5% of patients receiving transdermal buprenorphine.213 Other adverse nervous system effects reported in less than 1% of patients receiving transdermal buprenorphine include affect lability,213 agitation,213 apathy,213 confusional state,213 abnormal coordination,213 depersonalization,213 depressed mood,213 disorientation,213 attention disturbance,213 dysarthria,213 euphoric mood,213 gait disturbance,213 hallucination,213 loss of consciousness,213 depressed level of consciousness,213 malaise,213 memory impairment,213 mental impairment,213 mental status changes,213 nervousness,213 nightmare,213 psychotic disorder,213 restlessness,213 sedation,213 and vertigo.213

In clinical trials in patients receiving buprenorphine buccally dissolving strips for pain relief, fatigue,232 headache,232 dizziness,232 and somnolence232 were reported in at least 5% of patients receiving the buccally administered drug; anxiety,232 insomnia,232 and depression232 were reported in 1 to less than 5% of patients; and asthenia,232 hypoesthesia,232 lethargy,232 migraine,232 and tremor232 were reported in less than 1% of patients.232

Adverse nervous system effects reported in clinical trials in patients receiving sublingual buprenorphine or buprenorphine/naloxone for the treatment of opiate dependence include headache,202,214 insomnia,202,214 anxiety,202,214 depression,202,203,214 irritability,214 restlessness,214 asthenia,202,214 dizziness,202,214 nervousness,202,214 and somnolence.202,214 Intoxication and disturbance in attention also have been reported.214 In clinical trials in patients receiving buprenorphine/naloxone buccally dissolving strips, headache234 and lethargy234 were reported in at least 5% of patients, and insomnia,234 somnolence,234 and fatigue234 were reported in more than 1 to less than 5% of patients.234

In phase 3 clinical trials, headache,236 fatigue,236 somnolence,236 sedation,236 and dizziness236 were reported in less than 10% of patients receiving buprenorphine extended-release subcutaneous injection.236

In phase 3 clinical trials, headache237 and depression237 were reported in 6-13% and dizziness,237 somnolence,237 fatigue,237 asthenia,237 migraine,237 sedation,237 and paresthesia237 were reported in less than 5% of patients with buprenorphine subdermal implants.237

GI Effects

Nausea1,40,44,49,51,53,67,71,76,79,83,93,105,106,183,184,185,192 occurs in about 5-10% of patients receiving parenteral buprenorphine for pain relief1 and is accompanied by vomiting1,27,40,44,51,53,67,71,83,93,105,106,183,184,185,192 in about 1-5% of patients.1 Vomiting alone occurs in about 1-5% of these patients.1 Dry mouth,1,45,56,95,99,183 constipation,1,74,97,107,111 dyspepsia,1 abdominal cramps,183 and flatulence1,102 have occurred in less than 1% of patients receiving parenteral buprenorphine.1 Anorexia1,107,111 and diarrhea1 have been reported rarely.1

In clinical trials in patients receiving transdermal buprenorphine, the most frequent adverse GI effects were nausea (10-25% of patients),213,223 constipation (5-15%),213,223 vomiting (5-10%),213,223 and dry mouth (6%).213 Diarrhea,213 dyspepsia,213 stomach discomfort,213 anorexia,213 and upper abdominal pain213 have been reported in about 1-5% of patients receiving transdermal buprenorphine.213 Other adverse GI effects reported in less than 1% of patients receiving transdermal buprenorphine include abdominal distension,213 abdominal pain,213 diverticulitis,213 dysgeusia,213 dysphagia,213 flatulence,213 and ileus.213

In clinical trials in patients receiving buprenorphine buccally dissolving strips for pain relief, nausea,232 constipation,232 vomiting,232 diarrhea,232 and dry mouth232 were reported in at least 5% of patients receiving the buccally administered drug; abdominal pain,232 decreased appetite,232 and gastroenteritis232 were reported in 1 to less than 5% of patients; and abdominal discomfort,232 dyspepsia,232 toothache,232 and tooth abscess232 were reported in less than 1% of patients.232

Nausea,202,214 abdominal pain,202,214 constipation,202,214 vomiting,202,214 diarrhea,202,214 dyspepsia,202,214 and stomach discomfort214 have occurred in patients receiving sublingual buprenorphine or buprenorphine/naloxone for the treatment of opiate dependence in clinical trials.202,203,214 Oral hypoesthesia,202,214,233 glossodynia,202,214,233 glossitis,202,214,233 stomatitis,202,214,233 blistering and ulceration of the mouth or tongue,214 and oral mucosal erythema202,214,233 also have occurred with sublingual use of the drug.202,214,233 Constipation234 and oral mucosal erythema234 have been reported in less than 5% of patients receiving buprenorphine/naloxone buccally dissolving strips.234

In phase 3 clinical trials, constipation,236 nausea,236 and vomiting236 were reported in about 5-9% of patients receiving buprenorphine extended-release subcutaneous injection.236

Nausea,237 vomiting,237 constipation,237 upper abdominal pain,237 flatulence,237 and toothache237 were reported in phase 3 clinical trials in 1-6% of patients with buprenorphine subdermal implants.237

Hepatic Effects

Cytolytic hepatitis and hepatitis with jaundice have occurred in individuals receiving buprenorphine for the treatment of opiate dependence in clinical trials and during postmarketing experience.202,213,214 Adverse hepatic effects that have occurred in these individuals include transient asymptomatic elevations in serum hepatic aminotransferase concentrations, hepatic failure, hepatic necrosis, hepatorenal syndrome, and hepatic encephalopathy.202,213,214 In some individuals, preexisting hepatic enzyme abnormalities, hepatitis B virus (HBV) or hepatitis C virus (HCV) infection, concomitant use of potentially hepatotoxic drugs, or ongoing illicit use of injectable drugs may have contributed to or caused these adverse hepatic events.202,213,214 Data were insufficient in some cases to determine the etiology of the adverse event.202,214 The possibility exists that buprenorphine had a causative or contributory role in some of these adverse hepatic events.202,214

Increased ALT concentrations have been reported in clinical trials in less than 1% of patients receiving transdermal buprenorphine.213

In clinical trials in patients receiving buprenorphine buccally dissolving strips for pain relief, increased AST concentration232 and liver function test abnormality232 were reported in less than 1% of patients receiving the buccally administered drug.232

In phase 3 clinical trials, increased concentrations of ALT,236 AST,236 and γ-glutamyltransferase (GGT, γ-glutamyltranspeptidase, GGTP)236 were reported in about 1-5% of patients receiving buprenorphine extended-release subcutaneous injection.236

Cardiovascular Effects

Buprenorphine has the potential to prolong the QT interval.213 In a randomized, double-blind, placebo-controlled, single-dose study in 132 healthy adults, the effect of transdermal buprenorphine on the QT interval corrected for heart rate (QT_c) was evaluated under steady-state conditions (i.e., on day 3 of treatment with buprenorphine 10 mcg/hour and day 4 of treatment with buprenorphine 40 mcg/hour).213 Although the 10-mcg/hour dosage had no clinically meaningful effect on the QT_c interval, the 40-mcg/hour dosage prolonged the QT_c interval by a maximum of 9.2 msec.213 Therefore, the maximum recommended dosage of transdermal buprenorphine is 20 mcg/hour.213 In controlled and open-label clinical trials, prolongation of the QT_c interval (corrected for heart rate using Fridericia's formula) to 450-480 msec occurred in 2% of patients with chronic pain receiving buprenorphine buccally dissolving strips at dosages up to 900 mcg every 12 hours, which is the maximum recommended dosage of buccally dissolving strips.232

Hypotension1,21,45,61,66,74,78,82,89,95,97,107,111,185 has reportedly occurred in about 1-5% of patients receiving parenteral buprenorphine for pain relief.1 Other adverse cardiovascular effects, including hypertension,1,46,62 tachycardia,1,46,62,73,78,94,95 bradycardia,1,51,66,82,89,97,111 and ECG abnormalities manifested as Wenckebach period,1 have occurred in less than 1% of patients receiving parenteral buprenorphine for pain relief.1 Shock has occurred rarely.78

Peripheral edema213 and hypertension213 have been reported in clinical trials in about 1-5% of patients receiving transdermal buprenorphine.213 Other adverse cardiovascular effects reported in less than 1% of patients receiving transdermal buprenorphine include hypotension,213 orthostatic hypotension,213 angina pectoris,213 bradycardia,213 palpitation,213 syncope,213 tachycardia,213 and vasodilation.213 Hypotension may be severe, especially in patients with blood volume depletion and those receiving concomitant therapy with dugs that may compromise vasomotor tone (e.g., phenothiazines).213

In clinical trials in patients receiving buprenorphine buccally dissolving strips for pain relief, hypertension232 and peripheral edema232 were reported in 1 to less than 5% of patients receiving the buccally administered drug, and increased blood pressure232 and QT-interval prolongation232 were reported less than 1% of patients.232

Vasodilation has occurred in patients receiving sublingual buprenorphine or buprenorphine/naloxone for the treatment of opiate dependence in clinical trials.202,214 Peripheral edema and palpitations also have been reported.214

Respiratory Effects

Respiratory depression (decreased rate and depth of respiration) may occur occasionally in patients receiving parenteral buprenorphine.1,18,28,33,39,44,48,58,59,62,64,71,73,75,76,84,89,93,95,97,184,185,192 Respiratory depression requiring active treatment has occurred in less than 1% of patients receiving parenteral buprenorphine for pain relief.93,185 Hypoventilation1,96 has been reported in about 1-5% of these patients.1 Dyspnea,1 cyanosis,1,46 and apnea1,192 have been reported in less than 1% of these patients.1 Hypoxemia has occurred rarely.51

Dyspnea,213 cough,213 pharyngolaryngeal pain,213 upper respiratory infection,213,223 nasopharyngitis,213,223 influenza,213 sinusitis,213 and bronchitis213 have been reported in clinical trials in about 1-5% of patients receiving transdermal buprenorphine.213 Other adverse respiratory effects reported in less than 1% of patients receiving transdermal buprenorphine include aggravated asthma,213 rhinitis,213 hyperventilation,213 hypoventilation,213 abnormal respiration,213 respiratory depression,213 respiratory distress,213 respiratory failure,213 and wheezing.213

In clinical trials in patients receiving buprenorphine buccally dissolving strips for pain relief, upper respiratory infection232 was reported in at least 5% of patients receiving the buccally administered drug; nasopharyngitis,232 sinusitis,232 bronchitis,232 oropharyngeal pain,232 and sinus congestion232 were reported in at least 1% of patients; and acute sinusitis,232 cough,232 dyspnea,232 nasal congestion,232 and rhinorrhea232 were reported in less than 1% of patients.232

Rhinitis,202,214 rhinorrhea,214 increased cough,202,214 and pharyngitis202,214 have occurred in patients receiving sublingual buprenorphine or buprenorphine/naloxone for the treatment of opiate dependence in clinical trials.202,214 In clinical trials in patients receiving buprenorphine/naloxone buccally dissolving strips, rhinorrhea234 was reported in more than 1 to less than 5% of patients.234

Oropharyngeal pain,237 cough,237 and dyspnea237 were reported in phase 3 clinical trials in 1-5% of patients with buprenorphine subdermal implants.237

Naloxone1,9,19,20,21,40,44,70,71,84 and doxapram9,18,21,59,70,71,76,84,185 have been used to reverse buprenorphine-induced respiratory depression, but these agents may be only partially effective1,9,18,21,40,59,64,70,71,76,84,185 and, rarely, completely ineffective.1,40,64,192 Consequently, the principal management of respiratory depression induced by the drug should be assisted or controlled respiration and administration of oxygen as necessary.1,20,46,83

Sensitivity Reactions

Acute and chronic hypersensitivity reactions have been reported in patients receiving buprenorphine.202,213,214 Rash,202 urticaria,202 and pruritus202 are the most common manifestations of these hypersensitivity reactions.202 Bronchospasm,202 angioedema,202 and anaphylactic shock202 also have occurred in patients receiving the drug.202

Angioedema,213 hypersensitivity reaction,213 facial edema,213 and urticaria213 have been reported in clinical trials in less than 1% of patients receiving transdermal buprenorphine.213

Ocular Effects

Miosis1,67,74,89,111,174,192 occurs in about 1-5% of patients receiving parenteral buprenorphine.1 Blurred vision,1,55,56,183 diplopia,1,42,88,98 amblyopia,1 mydriasis,183 other visual abnormalities,1 and conjunctivitis1 have been reported in less than 1% of patients receiving parenteral buprenorphine for pain relief.1

Dry eye,213 miosis,213 blurred vision,213 and visual disturbance213 have been reported in clinical trials in less than 1% of patients receiving transdermal buprenorphine.213

Runny eyes,202,214 increased lacrimation,214 and blurred vision214 have been reported in patients receiving sublingual buprenorphine or buprenorphine/naloxone for the treatment of opiate dependence.202,214

Dermatologic Effects

Adverse dermatologic effects, including pruritus,1,31,57,96,106,107,183,185 reactions at the injection site,1,183 and rash,1,55,56,183 have occurred in less than 1% of patients receiving parenteral buprenorphine for pain relief.1 Urticaria1,107 has been reported rarely.1 Stevens-Johnson syndrome occurred in at least one patient receiving concomitant radiation and drug therapy that included parenteral buprenorphine; however, a causal relationship to buprenorphine was not established.104

Application site reactions, including pruritus, erythema, rash, and irritation,213,223 have been reported in about 5-15% of patients receiving transdermal buprenorphine in clinical trials.213 Severe application site reactions with marked inflammation, characterized by burning, discharge, or vesicles occurring days to months after initiation of therapy, also have occurred rarely.213 Application site dermatitis,213 contact dermatitis,213 and dry skin213 have been reported in less than 1% of patients receiving transdermal buprenorphine.213

In clinical trials in patients receiving buprenorphine buccally dissolving strips for pain relief, pruritus232 and rash232 were reported in 1 to less than 5% of patients receiving the buccally administered drug, and cellulitis232 was reported in less than 1% of patients.232

In phase 3 clinical trials in patients receiving buprenorphine extended-release subcutaneous injection, the most frequent injection site reactions were pain,236 pruritus,236 and erythema236 (each occurring in about 5-7% of patients); induration236 at the injection site was reported in 1.4% of patients; and bruising,236 swelling,236 discomfort,236 cellulitis,236 and infection236 at the injection site were reported in less than 1% of patients.236

Pain,237 pruritus,237 erythema,237 hematoma,237 hemorrhage,237 and edema237 at the implant site were reported in phase 3 clinical trials in 5-13% of patients with buprenorphine subdermal implants.237 Rash237 and skin lesion237 were reported in 1-2% of patients with buprenorphine implants.237

Genitourinary and Endocrine Effects

Urinary retention1,71,92,101,107,111 and decreased libido107 have been reported in less than 1% of patients receiving parenteral buprenorphine for pain relief.1 Flushing,213 hot flush,213 decreased libido,213 sexual dysfunction,213 urinary hesitancy,213 and urinary incontinence213 have been reported in less than 1% of patients receiving transdermal buprenorphine.213

In clinical trials in patients receiving buprenorphine buccally dissolving strips for pain relief, urinary tract infection232 and hot flush232 were reported in 1 to less than 5% of patients receiving the buccally administered drug, and decreased blood testosterone concentration232 was reported in less than 1% of patients.232

Adrenal insufficiency has been reported in patients receiving opiate agonists or opiate partial agonists.214,400 Manifestations of adrenal insufficiency are nonspecific and may include nausea, vomiting, anorexia, fatigue, weakness, dizziness, and hypotension.214,400 The onset generally has occurred after at least 1 month of opiate agonist or partial agonist use,214,400 although the time to onset has ranged from within 1 day to more than 1 year.400 In many of the reported cases, patients required hospitalization.400 If adrenal insufficiency is suspected, appropriate laboratory testing should be performed promptly and physiologic (replacement) dosages of corticosteroids provided; therapy with the opiate agonist or partial agonist should be tapered and discontinued to allow recovery of adrenal function.214,400 If the opiate agonist or partial agonist can be discontinued, follow-up assessment of adrenal function should be performed to determine if corticosteroid replacement therapy can be discontinued.400 In some patients, switching to a different opiate improved symptoms.214,400

Hypogonadism and androgen deficiency have been reported in patients receiving long-term opiate agonist or opiate partial agonist therapy,214,400,401,402,403,404 although a causal relationship has not been established.400 Patients receiving long-term opiate agonist or partial agonist therapy who present with manifestations of hypogonadism (e.g., decreased libido, impotence, erectile dysfunction, amenorrhea, infertility) should undergo laboratory evaluation.214,400

Other Adverse Effects

Diaphoresis1,9,42,44,48,56,71,75,99,106,183,184,185 occurs in about 1-5% of patients receiving parenteral buprenorphine for pain relief.1 Other adverse effects reported in less than 1% of these patients1 include flushing and a sensation of warmth,1,48,183 tremor,1,57 chills and a sensation of cold,1,183 hiccups,55 tinnitus,1,107,183 and pallor.1,103 Increased pressure in the common bile duct has occurred in some patients receiving parenteral buprenorphine for pain relief.1,21,40,52,54 Decreases in erythrocyte count, hemoglobin, hematocrit, sedimentation rate, and total serum protein concentration have been reported during prolonged administration of buprenorphine (1-2 months), but these effects were reversible upon discontinuance of the drug.111 Serum alkaline phosphatase concentrations also decreased during prolonged buprenorphine therapy and were not reversible upon discontinuance; however, values remained within the normal range.111

Hyperhidrosis,213 falls,213 pain213 (including pain in extremity, back, neck, or chest),213 pyrexia,213 urinary tract infection,213 joint swelling,213 arthralgia,213,223 muscle spasm,213 musculoskeletal pain,213 and myalgia213 have been reported in clinical trials in about 1-5% of patients receiving transdermal buprenorphine.213 Accidental injury,213 chills,213 dehydration,213 hiccups,213 muscle weakness,213 tinnitus,213 and weight loss213 have been reported in less than 1% of patients receiving transdermal buprenorphine.213

In clinical trials in patients receiving buprenorphine buccally dissolving strips for pain relief, anemia,232 contusion,232 falls,232 hyperhidrosis,232 muscle spasm,232 back pain,232 and pyrexia232 were reported in 1 to less than 5% of patients receiving the buccally administered drug, and chills,232 excoriation,232 laceration,232 musculoskeletal pain,232 and neck pain232 were reported in less than 1% of patients.232

Pain (including back pain),202,214 sweating,202,214 cold sweat,214 chills,202,214 fever,202,214 infection,202,214 abscess,214 flu syndrome,202,214 arthralgia,214 piloerection,214 and accidental injury202,214 have been reported in patients receiving sublingual buprenorphine or buprenorphine/naloxone for the treatment of opiate dependence in clinical trials.202,203,214 In clinical trials in patients receiving buprenorphine/naloxone buccally dissolving strips, chills234 and hyperhidrosis234 were reported in more than 1 to less than 5% of patients.234

In clinical trials, increased creatine kinase (CK, creatine phosphokinase, CPK) concentration236 was reported in up to about 5% of patients receiving buprenorphine extended-release subcutaneous injection.236

In phase 3 clinical trials, pain (including pain in back, chest, or extremity),237 pyrexia,237 chills,237 feeling cold,237 local swelling,237 laceration,237 excoriation,237 and scratch237 were reported in 1-6% of patients with buprenorphine subdermal implants.237

Opiate Withdrawal

Because of buprenorphine's antagonist activity, the drug may precipitate mild to moderate signs and symptoms of withdrawal in some patients physically dependent on opiates.1,87,100,112,183,202,213,214 Signs and symptoms of mild withdrawal may also appear following discontinuance of prolonged therapy with buprenorphine alone.71,84,100,112

Precautions and Contraindications

When the fixed-combination preparation containing buprenorphine and naloxone is used, the usual cautions, precautions, and contraindications associated with naloxone should be considered in addition to those associated with buprenorphine.202

Addiction, Abuse, and Misuse

Buprenorphine exposes patients and other users to the risks of opiate addiction, abuse, and misuse, which can lead to overdosage and death.213 Addiction can occur with appropriately prescribed or illicitly obtained opiate analgesics, and at recommended dosages or with misuse or abuse.213 Concurrent abuse of alcohol or other CNS depressants increases the risk of toxicity.213 Each patient's risk for addiction, abuse, and misuse should be assessed prior to initiating buprenorphine for analgesia, and all patients receiving the drug should be monitored for development of these behaviors or conditions.213 Personal or family history of substance abuse (drug or alcohol addiction or abuse) or mental illness (e.g., major depression) increases risk.213 The potential for addiction, abuse, and misuse should not prevent opiate prescribing for appropriate pain management, but does necessitate intensive counseling about risks and proper use and intensive monitoring for signs of addiction, abuse, and misuse.213 Buprenorphine should be prescribed for analgesia in the smallest appropriate quantity, and the patient should be instructed on secure storage and proper disposal to prevent theft.213

When used for treatment of opiate dependence (opiate use disorder [OUD]), buprenorphine should be prescribed and dispensed with appropriate precautions to minimize risk of misuse, abuse, or diversion, and to ensure appropriate protection from theft, including in the patient's home.214 Patients should be monitored for progression of opiate use disorder and addictive behaviors.236,237 Clinical monitoring appropriate to the patient's level of stability is essential.214 Multiple refills should not be authorized early in treatment or without appropriate patient follow-up visits.214

Extended-release opiates (e.g., buprenorphine transdermal system) are associated with a greater risk of overdosage and death because of the larger amount of drug contained in each dosage unit.213 Abuse or misuse of the transdermal system by placing it in the mouth, chewing it, swallowing it, or using it in other unintended ways may cause choking, overdosage, and death.213

Abuse or misuse of buprenorphine buccally dissolving strips by swallowing the strips may cause choking, overdosage, and death.232

Buprenorphine subdermal implants that protrude from the skin or have been expelled are subject to misuse and abuse.237

Respiratory and CNS Depression

Serious, life-threatening, or fatal respiratory depression may occur in patients receiving opiates, including buprenorphine, even when used as recommended.1,18,28,33,39,44,48,58,59,62,64,71,73,75,76,84,89,93,95,97,184,185,213,232 Although respiratory depression can occur at any time during therapy, the risk is greatest during initiation of therapy and following an increase in dosa therefore, patients receiving buprenorphine should be monitored closely for respiratory depression, especially during the first 24-72 hours of therapy and following any increase in dosage.1,213,232 Appropriate dosage selection and titration are essential to reduce the risk of respiratory depression.213,232 Large initial doses in nontolerant patients, overestimation of the initial buprenorphine dosage when transferring patients from another opiate analgesic, or accidental exposure to buprenorphine, especially by a child, can result in respiratory depression and death.213,232

The risk of respiratory depression is increased when opiates, including buprenorphine, are used concomitantly with other agents that cause respiratory depression.213 Many postmarketing reports of coma and death have involved misuse of buprenorphine by self-injection or were associated with the concomitant use of buprenorphine and benzodiazepines or other CNS depressants, including alcohol.214,236

Carbon dioxide retention from opiate-induced respiratory depression can exacerbate the drug's sedative effects and, in certain patients, can lead to elevated intracranial pressure.1,213,232

Geriatric, cachectic, or debilitated patients are at increased risk of life-threatening respiratory depression.1,213,232 In patients with chronic obstructive pulmonary disease or cor pulmonale, substantially decreased respiratory reserve, hypoxia, hypercapnia, or preexisting respiratory depression, even recommended doses of buprenorphine may decrease respiratory drive to the point of apnea.1,213,232 Such patients should be monitored closely, particularly following initiation of therapy, during dosage titration, and during concomitant therapy with other respiratory depressants.1,213,232 Alternatively, use of nonopiate analgesics should be considered in such patients.1,213,232 Use of buprenorphine formulations labeled for analgesic use is contraindicated in patients with substantial respiratory depression and in those with severe bronchial asthma in unmonitored settings or in the absence of resuscitative equipment.1,213,232

If therapy with buprenorphine extended-release subcutaneous injection is discontinued because of compromised respiratory function, the patient should be monitored for continued buprenorphine effects for several months.236

Because of the risks associated with opiate overdosage, clinicians should routinely discuss the availability of the opiate antagonist naloxone with all patients receiving new or reauthorized opiate prescriptions for pain management or new or reauthorized prescriptions for medications for treatment of OUD.750 Clinicians should consider prescribing naloxone for patients receiving opiate analgesics who are at increased risk of opiate overdosage (e.g., those receiving concomitant therapy with benzodiazepines or other CNS depressants, those with a history of opiate or substance use disorder, those with medical conditions that could increase sensitivity to opiate effects, those who have experienced a prior opiate overdose) and should strongly consider prescribing naloxone for all patients receiving medications for treatment of OUD.411,431,750 Clinicians also should consider prescribing naloxone when patients receiving opiates for pain management or for treatment of OUD have household members, including children, or other close contacts who are at risk for accidental ingestion or overdosage.750 Even if patients are not receiving an opiate for pain management or medication for treatment of OUD, a naloxone prescription should be considered if the patient is at increased risk of opiate overdosage (e.g., those with a current or past diagnosis of OUD, those who have experienced a prior opiate overdose).750

Since naloxone1,9,21,40,64,71,84 and doxapram1,9,18,21,59,70,71,76,84,185 may be only partially effective in reversing buprenorphine-induced respiratory depression, the use of assisted or controlled respiration may be necessary and should be considered the principal method of management.1,20,46,83

Concomitant Use of Benzodiazepines or Other CNS Depressants

Concomitant use of opiate agonists or opiate partial agonists and benzodiazepines or other CNS depressants (e.g., anxiolytics, sedatives, hypnotics, tranquilizers, muscle relaxants, general anesthetics, antipsychotics, other opiates, alcohol) may result in profound sedation, respiratory depression, coma, and death.213,214,416,417,418,700,701,702,703 Concomitant use of opiate analgesics and benzodiazepines or other CNS depressants should be reserved for patients in whom alternative treatment options are inadequate; the lowest effective dosages and shortest possible duration of concomitant therapy should be used, and the patient should be monitored closely for respiratory depression and sedation.213,700,703 Patients receiving buprenorphine and/or their caregivers should be apprised of the risks associated with concomitant therapeutic or illicit use of benzodiazepines, alcohol, or other CNS depressants.213,214,700,703 Concomitant use with alcohol should be avoided.213,214,700

Because the morbidity and mortality associated with untreated opiate addiction can outweigh the serious risks associated with concomitant use of opiate agonists or partial agonists and benzodiazepines or other CNS depressants, buprenorphine treatment for opiate addiction (i.e., medication-assisted treatment [MAT]) should not be categorically withheld from patients receiving benzodiazepines or other CNS depressants.214,706 These drugs should be tapered and discontinued, if possible, in patients receiving MAT.214,706 However, excluding or discharging patients from MAT because of benzodiazepine or CNS depressant use is not likely to prevent such concomitant use and may lead to use outside the treatment setting, which could result in more severe outcomes.706 Careful management can reduce the risks associated with concomitant use of benzodiazepines or other CNS depressants in patients receiving buprenorphine treatment for opiate addiction.706 Benzodiazepines are not the treatment of choice for anxiety or insomnia in patients receiving buprenorphine treatment for opiate addiction; other pharmacologic or nonpharmacologic therapies should be considered.214,706 Current evidence does not support dose limitations or other arbitrary limits on buprenorphine as a strategy for addressing concomitant benzodiazepine or other CNS depressant use in patients receiving MAT.214,706 However, in patients who are sedated at the time of a scheduled buprenorphine dose, the cause of sedation should be evaluated and omission or reduction of the buprenorphine dose may be appropriate.214,706

Precautions for minimizing risks associated with concomitant use of benzodiazepines or other CNS depressants in patients receiving MAT include the following:

• Patient education upon initiation of MAT regarding the risks associated with concomitant use of benzodiazepines or other CNS depressants;
• Development of strategies upon initiation of MAT for managing any prescribed or illicit use of benzodiazepines or other CNS depressants;
• Verification of the diagnosis in any patient receiving prescribed benzodiazepines or other CNS depressants for anxiety or insomnia, and consideration of other treatment options for these conditions;
• Possible adjustment of induction procedures and more intensive monitoring;
• Recognition that MAT may be required indefinitely and should be continued for as long as the patient derives benefit and MAT contributes to the intended treatment goals;
• Coordination of care to minimize risks and ensure that other prescribers are aware that the patient is receiving buprenorphine treatment; and
• Measures to confirm that prescribed drugs are being used as intended and are not being diverted or supplemented with illicit drugs;
• Toxicology screening to monitor for prescribed or illicit drug use.214,706

Selection of an Appropriate Formulation

Oral transmucosal preparations of buprenorphine that are intended for use in the treatment of opiate dependence should not be used for analgesia.202,214,233,234,235 Fatal overdosage has been reported following administration of 2 mg of sublingual buprenorphine for analgesia in opiate-naive individuals.202,214,233,234,235 Buprenorphine extended-release subcutaneous injection also should not be used in opiate-naive individuals.236 Safety and efficacy of transdermal buprenorphine for the management of opiate dependence have not been established.213

Accidental Exposure

Accidental exposure to buprenorphine can cause severe, possibly fatal, respiratory depression in children.214 Buprenorphine-containing preparations are involved in a disproportionate share of unsupervised prescription drug and opiate ingestions by children younger than 6 years of age.253,261 From 2004-2011, buprenorphine was involved in an estimated 24% of emergency department visits involving accidental opiate ingestion by children 1-5 years of age.253 Other surveillance data for 2010-2011 indicate that buprenorphine was involved in approximately 30% of emergency department visits and 60% of emergent hospitalizations involving opiate ingestion by children younger than 6 years of age.261 The surveillance data for 2010-2011 also indicate that approximately 96% of the reported emergency department visits involving buprenorphine ingestion in this age group involved buprenorphine/naloxone.261 Buprenorphine-containing preparations should be stored out of the sight and reach of children.213,214 Used transdermal systems and any drug that is no longer needed should be disposed of appropriately.213,214 Any subdermal implant that has been expelled from the skin should be kept away from others, especially from children.237

QT-Interval Prolongation

Prolongation of the QT interval corrected for heart rate (QT_c) has occurred in some patients receiving buprenorphine in clinical trials.1,232,236 In controlled and open-label clinical trials, prolongation of the QT_c interval (corrected for rate using Fridericia's formula) to 450-480 msec occurred in 2% of patients with chronic pain receiving buprenorphine buccally dissolving strips at dosages up to 900 mcg every 12 hours.232 In healthy adults, transdermal buprenorphine given in a dosage of 40 mcg/hour prolonged the QT interval.213 These findings should be taken into account when considering buprenorphine therapy in patients with hypokalemia, hypomagnesemia, or clinically unstable cardiac disease (e.g., unstable atrial fibrillation, symptomatic bradycardia, unstable congestive heart failure, active myocardial ischemia).1,213,232,236 Periodic ECG monitoring is recommended in such patients.1,232,236 Use of buprenorphine should be avoided in patients with a personal or family (i.e., immediate family member) history of long QT syndrome and in patients who are receiving class IA (e.g., quinidine, procainamide, disopyramide) or class III (e.g., sotalol, amiodarone, dofetilide) antiarrhythmic agents or other drugs known to prolong the QT interval.1,213,232,236 The maximum dosage of transdermal buprenorphine should not exceed 20 mcg/hour,213 and the maximum dosage of buprenorphine administered as buccally dissolving strips (Belbuca^®) should not exceed 900 mcg every 12 hours.232

Opiate Withdrawal

Misuse of oral transmucosal preparations of buprenorphine/naloxone via parenteral injection by individuals who are physically dependent on opiates is likely to produce marked and intense opiate withdrawal symptoms.202,214

Because of buprenorphine's opiate antagonist activity, it may precipitate withdrawal in patients physically dependent on opiates if administered before the agonistic effects of the full opiate agonist have subsided.87,100,112,147,183,202,233,236,237 To avoid precipitating withdrawal symptoms in patients currently receiving opiate analgesia, the dosage of the current opiate analgesic should be tapered to a dosage equivalent to no more than 30 mg daily of oral morphine sulfate prior to switching to buprenorphine.213,232 In patients initiating buprenorphine therapy for opiate dependence, induction therapy should be initiated when objective and clear signs of opiate withdrawal are evident.214,233,234,235,247,250 Prior to receiving therapy with buprenorphine implants or buprenorphine extended-release subcutaneous injection, patients should be stabilized on oral transmucosal therapy with the drug.236,237

Because abrupt discontinuance of buprenorphine or rapid reduction in dosage may result in withdrawal symptoms in patients who are physically dependent on the drug, dosage should be tapered gradually when therapy with the drug is discontinued.213,214

Prolonged maternal use of opiates during pregnancy can result in neonatal opiate withdrawal syndrome.213,214

Hepatic Impairment

Since buprenorphine is metabolized in the liver, the activity of the drug may be increased and/or prolonged in patients with hepatic impairment.1 Buprenorphine injection should be used with caution in patients with severe hepatic impairment.1 When buprenorphine buccally dissolving strips are used for analgesia, dosage adjustment is recommended in patients with severe hepatic impairment, and patients with either moderate or severe hepatic impairment should be monitored for toxicity or overdosage.232 Because buprenorphine transdermal system is intended for 7-day application, use of an alternative analgesic regimen that allows for greater dosage flexibility should be considered in patients with severe hepatic impairment.213

When oral transmucosal preparations of buprenorphine or buprenorphine/naloxone are used for the management of opiate dependence in patients with moderate or severe hepatic impairment, plasma concentrations of buprenorphine and naloxone are increased and half-lives of the drugs are prolonged.202,214,233,234,235 Naloxone is affected to a greater degree than buprenorphine, and the magnitude of the difference in effect is greater in individuals with severe hepatic impairment than in those with moderate hepatic impairment.202,214,234,235 This may result in an increased risk of precipitated withdrawal during the induction phase of treatment and interference with buprenorphine's efficacy throughout treatment.202,214,234,235 Buprenorphine/naloxone should be avoided in patients with severe hepatic impairment and may not be appropriate for those with moderate hepatic impairment.202,214,234,235 In patients with moderate hepatic impairment, buprenorphine/naloxone is not recommended for induction therapy but may be used with caution and careful monitoring for maintenance treatment following induction therapy with buprenorphine alone.202,214,234,235 Dosage adjustment of sublingual buprenorphine is recommended in patients with severe hepatic impairment, and patients with either moderate or severe hepatic impairment who are receiving the single-entity sublingual tablets should be monitored for toxicity or overdosage.233

Use of buprenorphine extended-release subcutaneous injection or buprenorphine subdermal implants is not recommended in patients with moderate to severe hepatic impairment since the extended-release injection does not allow for rapid adjustment of plasma buprenorphine concentrations and the implant dosage cannot be titrated.236,237 If moderate or severe hepatic impairment develops during therapy with buprenorphine extended-release subcutaneous injection or buprenorphine subdermal implants, the patient should be monitored for manifestations of toxicity or overdosage.236,237 If such manifestations occur in patients with buprenorphine implants, removal of the implants may be required.237 Patients who have received the extended-release subcutaneous injection should be monitored for several months; if manifestations of overdosage or toxicity occur within 2 weeks following an injection, the depot containing buprenorphine may be surgically excised, if necessary.236

Hepatotoxicity

Serious adverse hepatic events have occurred in patients receiving buprenorphine for the treatment of opiate dependence.213,214 While some individuals had risk factors for such adverse events (i.e., preexisting hepatic enzyme abnormalities, HBV or HCV infection, concomitant use of potentially hepatotoxic drugs, ongoing illicit use of injectable drugs), the possibility exists that buprenorphine had a causative or contributory role in some of these adverse hepatic events.213,214 In patients with opiate dependence, evaluation of liver function prior to initiation of buprenorphine therapy and periodically during treatment is recommended.214 The manufacturer of buprenorphine extended-release subcutaneous injection recommends monthly monitoring of liver function during treatment with this formulation, particularly in patients receiving the 300-mg dosage.236 Liver function also should be evaluated prior to initiation of buprenorphine therapy for analgesia and periodically during such treatment in patients at increased risk of hepatotoxicity (e.g., patients with a history of excessive alcohol intake, IV drug abuse, or liver disease).213,232 Careful biologic and etiologic evaluation is recommended in the event of an adverse hepatic event.214 In some patients, withdrawal of buprenorphine has resulted in amelioration of acute hepatitis; in other patients, no dosage reduction was necessary.214 If a decision is made to discontinue buprenorphine therapy, the drug should discontinued carefully to prevent withdrawal symptoms and, in patients being treated for opiate dependence, the return to illicit drug use; strict monitoring of the patient should be initiated.214

Hypotension

Buprenorphine may cause severe hypotension, including orthostatic hypotension and syncope, in ambulatory patients.213,214 Because the risk of severe hypotension is increased in patients whose ability to maintain blood pressure has been compromised by blood volume depletion or concomitant use of certain CNS depressants (e.g., phenothiazines, general anesthetics), such patients should be monitored for hypotension following initiation of buprenorphine therapy or an increase in buprenorphine dosage.213 Use of buprenorphine should be avoided in patients with circulatory shock since the drug may cause vasodilation that can further reduce cardiac output and blood pressure.213

Increased Intracranial Pressure or Head Injury

The respiratory depressant effects of opiates promote carbon dioxide retention, which can result in elevation of intracranial pressure.213 Patients who may be particularly susceptible to these effects (e.g., those with evidence of elevated intracranial pressure or brain tumors) should be monitored closely for sedation and respiratory depression, particularly during initiation of therapy.213 Opiates also may obscure the clinical course in patients with head injuries.213 Use of buprenorphine should be avoided in patients with impaired consciousness or coma.213

Seizures

Buprenorphine may increase the frequency of seizures in patients with seizure disorders and may increase the risk of seizures in some clinical settings associated with seizures.213 Patients with seizure disorders should be monitored for worsening of seizure control during buprenorphine therapy.213

GI Conditions

Opiates may increase serum amylase concentrations and cause spasm of the sphincter of Oddi.213 Patients with biliary tract disease, including those with acute pancreatitis, should be monitored for worsening symptoms.213 Buprenorphine formulations labeled for analgesic use are contraindicated in patients with known or suspected GI obstruction, including paralytic ileus.1,213,232

Like other opiates, buprenorphine may obscure the diagnosis and/or clinical course of acute abdominal conditions.214

Anesthesia and Analgesia in Patients Receiving Extended-release Injection or Implant Therapy for Opiate Dependence

When patients with buprenorphine subdermal implants or those who have received buprenorphine extended-release subcutaneous injection within the prior 6 months require anesthesia or analgesia for acute pain, nonopiate analgesics should be used whenever possible.236,237 Those patients requiring opiate analgesia may receive a high-affinity, full opiate agonist under clinician supervision, with particular attention given to respiratory function.236,237 Because higher doses may be required for analgesia, the potential for toxicity is increased.236,237 If opiates are a required component of anesthesia, patients should be continuously monitored in an anesthesia care setting by persons not involved in the conduct of the surgical or diagnostic procedure.236,237 Opiate therapy must be provided by individuals trained in the use of anesthetic drugs and the management of respiratory effects of potent opiates, specifically the establishment and maintenance of a patent airway and assisted ventilation.236,237

Implant Complications

Improper insertion of buprenorphine subdermal implants may result in rare but serious complications including nerve damage and implant migration resulting in embolism and death.237 Local migration, protrusion, and expulsion of implants also may occur.237 Protrusion or expulsion may be caused by incomplete insertion or infection at the insertion site and may result in accidental exposure to the drug.237 Buprenorphine implants should be inserted in accordance with the manufacturer's instructions.237 It is essential for each implant to be inserted subdermally so that it is palpable following insertion and for proper placement to be confirmed by palpation immediately after insertion.237

Neural or vascular injury may occur if buprenorphine implants are inserted into muscle or fascia.237 If an implant is inserted too deeply, cannot be palpated, or has migrated, removal may be complicated.237 Additional surgical procedures may be required to remove an implant that was inserted too deeply and cannot be readily localized.237 Injury to deeper neural or vascular structures may occur when deeply inserted implants are removed.237

Excessive palpation shortly after insertion or improper removal may increase the risk of infection at the implant site.237

Because of the risks associated with implant insertion and removal, buprenorphine implants are available only through a restricted distribution program (Probuphine^® REMS).237

Extended-release Subcutaneous Injection

Because buprenorphine extended-release subcutaneous injection forms a solid mass upon contact with body fluids, IV administration could result in death or serious complications (e.g., venous occlusion, local tissue damage, thromboembolic events including life-threatening pulmonary embolism).236 The extended-release subcutaneous injection should not be administered IV or by IM injection.236 Because of the risks associated with IV self-administration, the extended-release subcutaneous injection is available only through a restricted distribution program (Sublocade^® REMS).236

Transdermal Therapy

Patients receiving transdermal buprenorphine therapy who develop severe reactions with marked inflammation (e.g., burning, discharge, vesicles) at the application site should be advised to consult their clinician promptly about the need to remove the transdermal system.213

Because the absorption of topically applied buprenorphine from the transdermal system depends in part on the temperature of the skin and increases with increased temperature, patients who develop a fever while using the transdermal system and individuals whose core body temperature increases as a result of strenuous exercise should be observed closely for manifestations of opiate toxicity, and dosage of the drug should be adjusted if respiratory or CNS depression occurs.213 In addition, patients wearing a transdermal system of the drug should be advised to avoid exposing the application site or surrounding area to direct external heat sources.213

Dental Complications Associated with Transmucosal Buprenorphine Preparations

Adverse dental events, sometimes severe, have been reported following the use of transmucosal buprenorphine-containing preparations (i.e., tablets and films dissolved under the tongue or placed against the inside of the cheek available as single-ingredient products or in combination with naloxone).437 FDA has issued a drug safety communication about this risk.437

Since initial approval of buprenorphine, 305 cases of dental problems associated with the use of transmucosal buprenorphine have been reported to FDA or published in the medical literature; 131 cases were classified as serious.437 Reported events included cavities/tooth decay, including rampant caries; dental abscesses/infection; tooth erosion; fillings falling out; and, in some cases, total tooth loss.437 These dental complications have been reported in patients with or without prior history of dental issues.437 The average age of patients was 42 years, and the median time to diagnosis was 24.25 months.437 Most cases were reported in patients using buprenorphine for OUD; however, 28 cases occurred in patients receiving the drugs for pain treatment.437 Tooth extraction or removal was required in 71 cases; other dental interventions included root canals, dental surgery, crowns, and implants.437

Screen patients for oral disease and assess oral health history prior to prescribing transmucosal buprenorphine.437 Counsel patients about the potential for dental problems and the importance of taking extra steps after the drug has completely dissolved to reduce this risk, including gently rinsing teeth and gums with water and then swallowing.437 Advise patients to wait at least 1 hour before brushing their teeth.437 Refer patients to a dentist as soon as possible after starting transmucosal buprenorphine for a baseline dental evaluation and caries risk assessment and preventive plan; encourage regular dental checkups.437 Advise patients to not stop taking buprenorphine without first discussing with their health care professional as it could lead to serious consequences, including relapse to opioid misuse or abuse that could result in overdose and death.437 The benefits of buprenorphine clearly outweigh its risks.437

Buccal Buprenorphine in Cancer Patients with Mucositis

Cancer patients with oral mucositis may absorb buprenorphine from buccally dissolving strips (Belbuca^®) more rapidly than intended and are likely to achieve higher plasma concentrations of the drug.232 Dosage reduction and careful monitoring for toxicity or overdosage is recommended in patients with known or suspected mucositis receiving this formulation of the drug.232

Patient Advice

Patients should be advised to read the manufacturer's patient information (e.g., medication guide and any instructions for use of the prescribed formulation) for buprenorphine before initiating therapy with the drug and each time the prescription is refilled.213,214 Patients should be informed that use of buprenorphine, even when taken as recommended, can result in addiction, abuse, and misuse, which can lead to overdosage and death.213 Patients also should be informed that accidental exposure to buprenorphine, especially by a child, may result in respiratory depression or death.213,214 Patients should be instructed not to share the drug with others, to take steps to protect the drug from theft or misuse, to securely store the drug, to keep the drug out of reach of children, and to properly dispose of any unused drug.213,214

Patients should be advised of the risk of life-threatening respiratory depression and instructed to seek immediate medical attention if manifestations of respiratory depression occur.213 They also should be advised of the benefits of naloxone administration following an overdose and of their options for obtaining the drug.750 Patients receiving buprenorphine and/or their caregivers should be advised that concomitant therapeutic or illicit use of benzodiazepines or other CNS depressants, including alcohol, can result in potentially fatal additive effects (e.g., profound sedation, respiratory depression, coma); patients should be advised to avoid concomitant use of alcohol and to avoid concomitant use of other CNS depressants unless such use is supervised by a clinician.213,214,700 Patients should be advised that self-administration of benzodiazepines while taking buprenorphine is extremely dangerous.213

Patients should be advised of the importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, and herbal supplements, as well as any concomitant illnesses.213,214 Patients should be advised that buprenorphine should not be used concomitantly with or within 14 days following a monoamine oxidase (MAO) inhibitor213 and that concomitant use of buprenorphine and serotonergic drugs may cause serotonin syndrome.213,214,400

Patients should be advised that buprenorphine may impair mental or physical abilities required to perform potentially hazardous tasks such as driving a car or operating machinery and that they should avoid such activities until they know how the drug affects them.213,214 Patients also should be advised that severe hypersensitivity reactions (e.g., anaphylaxis) have occurred and that the drug may cause orthostatic hypotension and syncope.213,214 Because opiates can cause severe constipation, patients should be advised on appropriate management of constipation.213 Because of the potential risk of adrenal insufficiency, patients should be advised to immediately contact a clinician if manifestations of adrenal insufficiency (e.g., nausea, vomiting, anorexia, fatigue, weakness, dizziness, hypotension) develop.213,214,400 Although a causal relationship between hypogonadism or androgen deficiency and long-term opiate use has not been established, patients should be advised of this potential risk and instructed to inform their clinician if decreased libido, impotence, erectile dysfunction, amenorrhea, or infertility occurs.400

Women of childbearing potential should be instructed to inform their clinician if they are or plan to become pregnant or plan to breast-feed.213,214 Risks and benefits of buprenorphine therapy should be discussed with pregnant and nursing women in the context of the intended use (pain management, treatment of opiate dependence).254,256 Women of childbearing potential should be advised that prolonged use of opiates during pregnancy may result in neonatal opiate withdrawal syndrome, which can be life-threatening if not recognized and treated.213,214 Nursing women should be advised to monitor their breast-fed infants for drowsiness or difficulty breathing.214

Patients should be instructed on proper administration of the prescribed dosage form and instructed not to alter the dosage without consulting their clinician.202,213,214,232,233,234,235 Patients receiving oral transmucosal therapy with buprenorphine or buprenorphine/naloxone for treatment of opiate dependence should be instructed that if a dose of the drug is missed, the missed dose should be taken as soon as it is remembered; however, if it is almost time for the next dose, the missed dose should be skipped and the regular schedule resumed with the next dose.202,214,233

Patients should be informed that buprenorphine can cause physical dependence and that gradual tapering of the dosage may be required to prevent withdrawal symptoms when the drug is discontinued.213,214 Patients receiving buprenorphine or buprenorphine/naloxone for maintenance treatment of opiate dependence should be advised of the potential for relapse to illicit drug use upon discontinuance of maintenance treatment.214

Patients receiving buprenorphine as an analgesic should be instructed to inform their clinician of any breakthrough pain or adverse effects that occur, so that therapy may be adjusted based on individual patient requirements.213

Patients receiving buprenorphine or buprenorphine/naloxone for treatment of opiate dependence should be advised to instruct their family members that, in the event of an emergency, they should inform the treating clinician or emergency department staff that the patient is physically dependent on opiates and is receiving treatment with an oral transmucosal or long-acting formulation of the drug.214,236,237

Patients receiving therapy with buprenorphine extended-release subcutaneous injection should be informed that the drug may be detectable for a prolonged time after administration and that drug effects and other associated precautions and considerations (e.g., risk of drug interactions, risks associated with treatment of emergent acute pain) may persist for several months after the last injection.236 Patients should be informed that a lump may develop at the injection site and that it will gradually diminish in size.236 Patients should be instructed not to tamper with or attempt to remove the solid depot containing buprenorphine and should be advised that the extended-release subcutaneous injection is available only under a restricted distribution program because of the risk of serious harm or death if the formulation is self-administered IV.236

Patients receiving buprenorphine subdermal implants should be instructed on appropriate care of the incision and should be advised of potential complications resulting from insertion or removal procedures, including neural or vascular injury, infection, and implant migration with the potential for embolism or nerve damage.237 Patients should be informed that complications may be more likely during removal if the implants were inserted too deeply or were manipulated by the patient or if the patient has gained substantial weight following insertion.237 Patients also should be informed that implant removal carries risks inherent to other minor surgical procedures, improper removal may result in infection, and premature removal may induce withdrawal symptoms.237 Patients should be informed that there is a risk to others of accidental overdosage, misuse, and abuse if an implant protrudes from the skin or is expelled; patients should be instructed on safety precautions that they must follow prior to seeing their clinician for such events.237 Patients should be advised that buprenorphine implants are available only under a restricted distribution program and must be inserted and removed in the facility of a certified prescriber.237

Patients receiving buprenorphine transdermal systems should be advised to avoid exposing the application site or surrounding area to direct external heat sources, hot water, or prolonged direct sunlight since such exposure can increase absorption of the drug.213

Contraindications

Buprenorphine is contraindicated in patients with known hypersensitivity to the drug or any components of the formulation.1,202,213,214 In addition, buprenorphine/naloxone is contraindicated in patients with known hypersensitivity to naloxone.202,214 Buprenorphine formulations labeled for analgesic use are contraindicated in patients with known or suspected GI obstruction (including paralytic ileus), substantial respiratory depression, or acute or severe bronchial asthma in an unmonitored setting or in the absence of resuscitative equipment.1,213,232

Pediatric Precautions

Safety and efficacy of buprenorphine conventional injection in children 2-12 years of age is supported by evidence from adequate and well-controlled trials in adults, with additional data from studies including 960 children and adolescents 9 months to 18 years of a data are available from a pharmacokinetic study, several controlled clinical trials, and several large postmarketing studies and case series.1,27,94 The manufacturer states that there is reasonable evidence of safety in children 2-12 years of age and efficacy similar to that observed in adults.1 Safety and efficacy of buprenorphine injection for pain relief in children younger than 2 years of age have not been established.1

Safety and efficacy of buprenorphine buccally dissolving strips for pain relief in pediatric patients have not been established.232 Safety and efficacy of transdermal buprenorphine for pain relief in patients younger than 18 years of age have not been established.213

Safety and efficacy of buprenorphine sublingual tablets, buprenorphine/naloxone sublingual tablets, or buprenorphine/naloxone buccally or sublingually dissolving strips for the management of opiate dependence in pediatric patients have not been established.202,214,233,234,235 Naloxone-containing preparations are not appropriate for management of neonatal opiate withdrawal syndrome.202,214,234,235

Safety and efficacy of buprenorphine extended-release subcutaneous injection for the treatment of opiate dependence in pediatric patients have not been established.236 Safety and efficacy of buprenorphine subdermal implants for treatment of opiate dependence have not been established in pediatric patients younger than 16 years of age.237

Geriatric Precautions

When the total number of patients studied in clinical trials of transdermal buprenorphine or buprenorphine buccally dissolving strips for pain relief is considered, approximately 25 or 16%, respectively, were 65 years of age or older, while about 8 or 2%, respectively, were 75 years of age and older.213,232 The pharmacokinetic profiles of these analgesic formulations in geriatric adults appear to be similar to those in younger adults.213,232 The safety profile of transdermal buprenorphine in healthy geriatric individuals appears to be similar to that in younger adults; however, constipation and urinary retention may occur more frequently in geriatric individuals.213 In clinical trials of buprenorphine buccally dissolving strips in patients with chronic pain, some adverse effects also occurred more frequently in geriatric patients.232 Other reported clinical experience with buprenorphine has not identified differences in responses between geriatric and younger adults.232 While specific dosage adjustments of transdermal buprenorphine or buprenorphine buccally dissolving strips are not necessary based on age, buprenorphine should be used with caution in geriatric patients.213,232 Because geriatric patients may have increased sensitivity to the drug, the manufacturer of buprenorphine injection states that dosage in geriatric patients should be selected with caution, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, and/or cardiac function and of concomitant disease or other drug therapy.1 Because respiratory depression is the chief risk for geriatric patients receiving opiate analgesics,1,213 buprenorphine dosage should be titrated slowly and the patient should be monitored closely for CNS and respiratory depression.1,213,232

Clinical studies of buprenorphine subdermal implants for the treatment of opiate dependence did not include patients older than 65 years of age237 and clinical studies of buprenorphine sublingual tablets, buprenorphine/naloxone sublingual tablets, buprenorphine/naloxone buccally or sublingually dissolving strips, and buprenorphine extended-release subcutaneous injection did not include sufficient numbers of patients 65 years of age or older to determine whether geriatric patients respond differently than younger adults.202,214,233,234,235,236 However, other reported clinical experience with buprenorphine has not revealed age-related differences in response.202,214,233,234,235,236,237 Because of age-related decreases in hepatic, renal, and/or cardiac function and the potential for concomitant disease and drug therapy, the decision to use buprenorphine or buprenorphine/naloxone for the treatment of opiate dependence in patients 65 years of age or older should be made cautiously, and these patients should be monitored for toxicity or overdosage.202,214,233,234,235,236,237

Pregnancy, Fertility, and Lactation

Pregnancy

Animal Reproduction Studies

Reproduction studies in rats and rabbits using IM or subcutaneous buprenorphine dosages up to 5 mg/kg daily (3 and 6 times, respectively, the human exposure on a mg/m² basis of a sublingual dosage of 16 mg daily), transdermal dosages of 20 mcg/hour in rats and 80 mcg/hour in rabbits (110 times the human exposure at a transdermal dosage of 20 mcg/hour), oral dosages of 160 mg/kg daily in rats or 25 mg/kg daily in rabbits (approximately 95 or 30 times, respectively, a human sublingual dosage of 16 mg daily), and IV dosages up to 0.8 mg/kg daily in rats and rabbits (0.5 and 1 times, respectively, the human exposure on a mg/m² basis of a sublingual dosage of 16 mg daily) have not revealed evidence of teratogenicity, although an increase in skeletal abnormalities (e.g., extra rib formation) occurred in rats receiving a subcutaneous dosage of 1 mg/kg daily (0.6 times the human exposure on a mg/m² basis of a sublingual dosage of 16 mg daily).186,213,214

Studies in rats and rabbits using buprenorphine (in a 1:1 ratio with naloxone) at oral dosages up to 250 mg/kg daily in rats and 40 mg/kg daily in rabbits (approximately 150 and 50 times, respectively, the human exposure on a mg/m² basis of a sublingual dosage of 16 mg daily) have not revealed evidence of teratogenicity.214 Studies in rats and rabbits using buprenorphine (in a 3:2 ratio with naloxone) at IM dosages of up to 30 mg/kg daily (20 and 35 times, respectively, the human exposure on a mg/m² basis of a sublingual dosage of 16 mg daily) have not revealed definitive drug-related teratogenic effects; acephalus was observed in one rabbit fetus from the low-dose group, omphalocele was observed in 2 rabbit fetuses from the same litter in the medium-dose group, and no teratogenic effects were observed in fetuses from the high-dose group.214

Buprenorphine has been shown to increase pregnancy loss in rats and rabbits.214 Dose-related postimplantation loss occurred in rats at oral dosages of 10 mg/kg daily (approximately 6 times the human exposure on a mg/m² basis of a sublingual dosage of 16 mg daily); postimplantation loss also occurred in rats at IM dosages of 30 mg/kg daily.214 In rabbits, increased preimplantation loss occurred at oral dosages of 1 mg/kg daily and increased postimplantation loss occurred at IV dosages of 0.2 mg/kg daily (both approximately 0.3 times the human exposure on a mg/m² basis of a sublingual dosage of 16 mg daily).214 Increased postimplantation loss also was observed in rabbits at oral dosages of 40 mg/kg daily and IM dosages of 30 mg/kg daily.214

Transdermal or subcutaneous buprenorphine caused maternal toxicity in rats and increased the number of stillborns, reduced litter size, and reduced offspring growth at maternal rat exposure levels that were approximately 10 times those observed with a human transdermal dosage of 20 mcg/hour.213 Dystocia occurred in pregnant rats receiving IM dosages of 5 mg/kg daily (approximately 3 times the human sublingual dosage of 16 mg daily on a mg/m² basis).214 An increase in rat neonatal mortality was observed with oral, IM, or subcutaneous dosages of 0.8, 0.5, or 0.1 mg/kg daily (approximately 0.5, 0.3, or 0.06 times, respectively, the human sublingual dosage of 16 mg daily on a mg/m² basis).214 An apparent lack of milk production during reproduction studies in rats likely contributed to decreased pup survival.214 Oral dosages of 80 mg/kg daily (approximately 50 times the human sublingual dosage of 16 mg daily on a mg/m² basis) were associated with delayed occurrence of the righting reflex and startle response in rat pups.214

In studies in rats using a solvent ( N -methyl-2-pyrrolidone; NMP) contained in the Atrigel^® vehicle of buprenorphine extended-release subcutaneous injection (Sublocade^®), preimplantation loss, delayed ossification, reduced fetal weight, and developmental delays and impaired cognitive function in pups born to NMP-exposed animals occurred at inhaled NMP dosages approximately equivalent to the amount of NMP provided by the recommended human dose of the Sublocade^® formulation; fetal malformations and resorption occurred at oral NMP dosages approximately 3 times that provided by the human dose of this buprenorphine formulation.236 Decreased pup survival occurred at oral maternal NMP dosages of 1.8 times that provided by the maximum recommended human dose of the Sublocade^® formulation.236 In rabbits, postimplantation loss and increased cardiovascular and skull malformations occurred at oral NMP dosages of 3.2 times the amount of NMP provided by the maximum recommended human dose of this formulation.236

In studies in rats using the Sublocade^® formulation at subcutaneous buprenorphine dosages of approximately 38 times the maximum recommended human dosage, embryolethality (which appeared to be attributable principally to the vehicle), reduced fetal body weight, and increased visceral and skeletal (principally skull) malformations occurred.236 These effects also were observed with the Atrigel^® vehicle alone, but the skeletal and visceral malformations appeared to be at least partially attributable to buprenorphine.236 In studies in rabbits using the Sublocade^® formulation, increased skeletal malformations (which appeared to be related to buprenorphine) occurred at a subcutaneous buprenorphine dosage of 7 times the maximum recommended human dosage.236 Increased malformations (external malformations, visceral malformations, skeletal malformations and variations), embryolethality, and decreased fetal body weight occurred at a subcutaneous buprenorphine dosage of approximately 15 times the maximum recommended human dosage and appeared to be attributable to the vehicle.236

Clinical Experience

Limited data from clinical trials, observational studies, case series, and case reports on use of buprenorphine during pregnancy do not indicate an increased risk of major malformations specifically due to the drug.214 However, interpretation is complicated by maternal factors such as illicit drug use, late presentation for prenatal care, poor nutritional status, presence of infections, poor compliance, and psychosocial circumstances and by the lack of comparative data for untreated opiate-dependent pregnant women.214 Comparisons generally have been made to women receiving a different opiate for medication-assisted treatment of opiate dependence or to women in the general population, who may differ from buprenorphine-treated women in their risk factors for poor pregnancy outcomes.214

In a double-blind, randomized, controlled trial (Maternal Opioid Treatment: Human Experimental Research [MOTHER]), outcomes, principally opiate withdrawal effects, were assessed in neonates born to women who received buprenorphine or methadone treatment for opiate dependence during pregnancy.214,257 Enrollment in the study occurred at an average gestational age of 18.7 weeks.214,257 Prior to the end of pregnancy, 33% of buprenorphine-treated women and 18% of methadone-treated women discontinued treatment; outcomes were evaluated for the neonates whose mothers remained in treatment until delivery.214,257 No difference was observed between buprenorphine- and methadone-exposed neonates in the proportion of neonates requiring treatment for opiate withdrawal syndrome or the peak severity of the syndrome.214,257 Buprenorphine-exposed neonates required a lower total mean morphine sulfate dosage for treatment of withdrawal (1.1 versus 10.4 mg), had shorter hospital stays (10 versus 17.5 days), and shorter duration of treatment for withdrawal (4.1 versus 9.9 days) compared with methadone-exposed neonates.214,257 The groups did not differ in other outcome measures (head circumference, weight and length at birth, preterm birth, gestational age at delivery, and 1- and 5-minute Apgar scores) or in the rates of serious maternal or neonatal adverse events.214,257 The imbalance in treatment discontinuance rates between buprenorphine- and methadone-treated women complicate interpretation of the study findings.214

Untreated opiate addiction during pregnancy is associated with adverse obstetrical outcomes, including preeclampsia, fetal growth restriction, preterm birth, spontaneous abortion, and fetal death.214,247,256 In addition, untreated opiate addiction often results in continued or relapsing illicit opiate use and engagement in high-risk behaviors.214,256 The recommended treatment of opiate dependence in pregnant women is maintenance treatment with buprenorphine or methadone; this approach is superior to medically supervised withdrawal because withdrawal is associated with high relapse rates and poorer outcomes.247,248,254,256

Use of a single-entity buprenorphine preparation is recommended during pregnancy247,248 to protect the fetus from any potential exposure to naloxone, especially if the fixed-combination preparation is injected, and also to avoid precipitated withdrawal in the event of IV injection.247,254,256 However, expert opinion regarding use of buprenorphine versus buprenorphine/naloxone during pregnancy appears to be evolving.247,254,256 Recent studies suggest that neonatal outcomes are similar with buprenorphine/naloxone or buprenorphine;247,254,256 if additional safety data confirm these findings, buprenorphine/naloxone use during pregnancy may increase, since the single-entity preparation has a higher risk for misuse and diversion.256 The manufacturers of buprenorphine/naloxone preparations currently state that the extremely limited data on sublingual naloxone exposure in pregnancy are not sufficient to evaluate a drug-associated risk.202,214,234,235

The manufacturer states that buprenorphine extended-release subcutaneous injection should be used during pregnancy only if the potential benefits justify the potential risks to the fetus.236 Based on animal data, pregnant women should be advised of the potential risk of this formulation to the fetus.236 There are no adequate and well-controlled studies to date with use of buprenorphine subdermal implants in pregnant women.237

Dosage adjustments of buprenorphine may be required during pregnancy, even if the patient was receiving a stable dosage prior to pregnancy.214,254 Pregnant women receiving buprenorphine should be monitored closely for withdrawal manifestations and the dosage adjusted as necessary.214

Opiate-dependent women receiving buprenorphine maintenance therapy may require additional analgesia during labor.214,256 When opiate analgesics are required during the intrapartum period, higher than usual dosages generally are needed to achieve adequate analgesia because of tolerance to the maintenance treatment dosage.256

Opiate analgesics, including buprenorphine, cross the placenta252 and may produce respiratory depression in neonates.1 The manufacturer states that safety of buprenorphine injection when administered during labor and delivery has not been established.1 Opiate analgesics, including buprenorphine, may prolong labor through actions that temporarily reduce the strength, duration, and frequency of uterine contractions.213 However, this effect is inconsistent and may be offset by an increased rate of cervical dilatation, which tends to shorten labor.213 Transdermal buprenorphine and buprenorphine buccally dissolving strips should not be used for pain relief in women immediately prior to or during labor, when use of shorter-acting analgesics or other analgesic techniques is more appropriate.213,232 Neonates exposed to opiates during labor should be monitored for respiratory depression.1 An opiate antagonist must be available for reversal of opiate-induced respiratory depression.213

Prolonged maternal use of opiates, including buprenorphine, during pregnancy can result in physical dependence in the neonate and neonatal opiate withdrawal syndrome.213,214 Manifestations may include irritability, hyperactivity and abnormal sleep pattern, high-pitched cry, tremor, vomiting, diarrhea, and failure to gain weight.213,214 In contrast to adults, the withdrawal syndrome in neonates may be life-threatening if not recognized and treated, and requires management according to protocols developed by neonatology experts.213,214 Women who require prolonged opiate agonist therapy during pregnancy should be advised of the risk of neonatal opiate withdrawal syndrome, and availability of appropriate treatment should be ensured.213,214 The onset, duration, and severity of the syndrome vary depending on the specific opiate agonist used, duration of use, timing and amount of last maternal use, and rate of drug elimination by the neonate.213 In neonates who have been exposed to buprenorphine, the onset of neonatal withdrawal symptoms generally occurs in the first 1-2 days after birth.256 Neonates born to women taking opiates chronically should be closely observed for signs of withdrawal.213,214

Fertility

Long-term use of opiates may reduce fertility in females and males of reproductive potential.213,214 It is not known whether these effects on fertility are reversible.213,214 Long-term use of opiates may influence the hypothalamic-pituitary-gonadal axis, resulting in androgen deficiency that may be manifested as low libido, impotence, erectile dysfunction, amenorrhea, or infertility.213,214 The causal role of opiates in hypogonadism is unknown because studies to date have not adequately controlled for other potential influences on gonadal hormone levels (e.g., medical or physical factors, lifestyle, psychological stressors).213,214

Reproduction studies in rats using IM and subcutaneous buprenorphine have not revealed evidence of impaired fertility.1 Reduced conception rates were observed in female rats receiving dietary buprenorphine dosages of approximately 47 mg/kg daily (approximately 28 times the human exposure on a mg/m² basis of a sublingual dosage of 16 mg daily).214 No evidence of impaired fertility or reproductive performance was observed in rats receiving transdermal buprenorphine in dosages resulting in AUCs up to 65 (in females) or 100 (in males) times the exposure level in humans receiving a transdermal dosage of 20 mcg/hour.213

However, adverse effects on sperm (low motility, low sperm count, and higher percentage of abnormal sperm) were observed in rats at a buprenorphine dose of 600 mg/kg (as buprenorphine extended-release subcutaneous injection [Sublocade^®]) and with the corresponding dose of the Atrigel^® vehicle contained in the drug injection.236 No effects on female mating, fertility, or fecundity indices were observed at subcutaneous extended-release buprenorphine dosages up to 900 mg/kg (approximately 38 times the maximum recommended human dose based on AUC comparison).236 Adverse effects on testes and male fertility also have been observed in rats receiving a solvent ( N -methyl-2-pyrrolidone; NMP) contained in the Atrigel^® vehicle for 10 weeks at a daily oral dosage greater than 11.6 times the amount of solvent delivered by the maximum recommended human dosage.236

Lactation

Buprenorphine is distributed into milk in humans.1,202,213,214 In 2 studies that included 13 nursing women receiving maintenance treatment with sublingual buprenorphine (2.4-24 mg daily) for opiate dependence, buprenorphine and its metabolite norbuprenorphine were present in low concentrations in milk and in the breast-fed infant's urine; the infants were exposed to less than 1% of the maternal daily buprenorphine dosage.214 In the first study in 6 women receiving buprenorphine (median dosage of 0.29 mg/kg daily) at 5-8 days postpartum, breast milk provided a median infant dosage of 0.42 mcg/kg daily of buprenorphine and 0.33 mcg/kg daily of norbuprenorphine (0.2 and 0.12%, respectively, of the maternal weight-adjusted dosage).214 In the other study in 7 women receiving buprenorphine (median dosage of 7 mg daily) at an average of 1.12 months postpartum, mean milk concentrations of buprenorphine and norbuprenorphine were 3.65 and 1.94 mcg/L, respectively; based on the results of this study, an exclusively breast-fed infant consuming 150 mL/kg daily of milk would receive a mean estimated dosage of 0.55 mcg/kg daily of buprenorphine and 0.29 mcg/kg daily of norbuprenorphine (0.38 and 0.18%, respectively, of the maternal weight-adjusted dosage).214 Adverse reactions in nursing infants were not observed.214

Experts recommend that women who are stable on buprenorphine or buprenorphine/naloxone treatment for opiate dependence, are not using other illicit drugs, and have no contraindications to nursing be encouraged to breast-feed their infants; to lower the risk of return to substance use, women receiving buprenorphine should be encouraged to continue treatment during the postpartum period.254,255,256 Breast-feeding has been associated with decreased severity of neonatal opiate withdrawal syndrome, decreased need for pharmacotherapy, and shorter hospital stays for the neonate.252,254,256 The manufacturers of buprenorphine-containing preparations used for treatment of opiate dependence state that developmental and health benefits of breast-feeding should be considered along with the mother's clinical need for buprenorphine or buprenorphine/naloxone and any potential adverse effects on the breast-fed child from the drug or from the underlying maternal condition.202,214,233,234,235,236,237 Because of the potential for serious adverse reactions, including excess sedation and respiratory depression in nursing infants, the manufacturers of buprenorphine preparations labeled for use as analgesics state that women should be advised not to nurse an infant while receiving the drug.1,213,232 Infants who are exposed to buprenorphine through breast milk should be monitored for excess sedation and respiratory depression.213,214,232

Symptoms of withdrawal can occur in opiate-dependent infants when maternal administration of opiates is discontinued or breast-feeding is stopped.213,232

Drug interactions that reportedly occur with other opiate agonists may also potentially occur during administration of buprenorphine.1

Benzodiazepines and Other CNS Depressants

Concomitant use of opiate agonists or opiate partial agonists, including buprenorphine, and benzodiazepines or other CNS depressants (e.g., anxiolytics, sedatives or hypnotics,35,42,59,64 tranquilizers,37,60 muscle relaxants, general anesthetics, antipsychotics, other opiates,75 alcohol) may result in profound sedation, respiratory depression, hypotension, coma, and death.1,213,416,417,418,700,701,702,703 Opiate analgesics frequently are implicated as contributing to fatal overdoses involving other CNS depressants, and epidemiologic studies have shown that a substantial proportion of fatal opiate overdoses involve the concurrent use of benzodiazepines, alcohol, or other CNS depressants.416,417,418,435,700,701,702 Whenever possible, concomitant use of opiates and benzodiazepines should be avoided.410,411,415,435 Alcohol also should be avoided in patients receiving opiates.213,700 Concomitant use of opiate analgesics and benzodiazepines or other CNS depressants should be reserved for patients in whom alternative treatment options are inadequate; the lowest effective dosages and shortest possible duration of concomitant therapy should be used, and the patient should be monitored closely for respiratory depression and sedation.1,213,700,703

If a benzodiazepine or other CNS depressant is required for any indication other than epilepsy in a patient receiving buprenorphine for analgesia, the drug should be initiated at a lower dosage than indicated in the absence of opiate therapy and titrated based on clinical response.700,703 In patients receiving a CNS depressant, buprenorphine, if required for analgesia, should be initiated at a reduced dosage and titrated based on clinical response.1,213,700,703

Because the morbidity and mortality associated with untreated opiate addiction can outweigh the serious risks associated with concomitant use of opiate agonists or partial agonists and benzodiazepines or other CNS depressants, buprenorphine treatment for opiate addiction (i.e., medication-assisted treatment [MAT]) should not be categorically withheld from patients receiving benzodiazepines or other CNS depressants.214,706 Clinicians should develop treatment plans that minimize the risks associated with concomitant use.214,706 If possible, benzodiazepines or other CNS depressants should be tapered and discontinued.214,706 (See Concomitant Use of Benzodiazepines or Other CNS Depressants under Cautions: Precautions and Contraindications.)

Clinicians should consider prescribing the opiate antagonist naloxone for patients receiving opiates who are at increased risk of opiate overdosage, including those receiving benzodiazepines or other CNS depressants concomitantly.411,431,750 (See Respiratory and CNS Depression under Cautions: Precautions and Contraindications.)

There have been reports of death or coma when buprenorphine was misused, often via self-injection of crushed tablets, or used concomitantly with benzodiazepines or other CNS depressants, including alcohol.202,213,214 In addition, results of preclinical studies indicate that the combination of benzodiazepines and buprenorphine may alter the usual ceiling on buprenorphine-induced respiratory depression, making the respiratory-depressant effects of buprenorphine, an opiate partial agonist, appear similar to those of opiate agonists.213 Patients receiving treatment with buprenorphine should be warned of the potential danger of self-administration of benzodiazepines or other CNS depressants, including IV self-administration.202,213,214

Respiratory and cardiovascular collapse has occurred in several patients receiving usual doses of IV buprenorphine and oral diazepam concomitantly;59 the patients recovered following treatment that included assisted respiration and IV doxapram.59 Bradycardia, respiratory depression, and prolonged drowsiness occurred following IV administration of buprenorphine during surgery in a patient who had received oral lorazepam preoperatively.36 The patient recovered following treatment that included IV atropine and assisted respiration; however, drowsiness persisted for more than 12 hours, and lack of awareness and recall of the surgical procedure (amnesia) reportedly lasted for 48 hours.36

Concomitant administration of buprenorphine and fentanyl produced satisfactory analgesia of prolonged duration, minimal respiratory depression, and allowed the patient to be aroused quickly and easily following surgery.70

Concomitant administration of buprenorphine and droperidol produced satisfactory analgesia during and after surgery60 and also in a terminally ill patient with severe, chronic pain that was previously unresponsive to buprenorphine therapy alone.37 In a group of patients who received a single, high dose of buprenorphine before undergoing cholecystectomy with balanced anesthesia and experienced pain in the immediate postoperative phase, addition of naloxone reportedly resulted in adequate analgesia, possibly by counteracting dominant antagonistic effects of buprenorphine.58,148

Drugs Affecting Hepatic Microsomal Enzymes

Buprenorphine metabolism is mediated principally by cytochrome P-450 (CYP) isoenzyme 3A4.1,202 Buprenorphine and its major metabolite (norbuprenorphine) also undergo conjugation with glucuronic acid.1,202

CYP3A4 Inhibitors

Concomitant use of buprenorphine with drugs that inhibit CYP3A4 (e.g., macrolide antibiotics [e.g., erythromycin], azole antifungals [e.g., ketoconazole], protease inhibitors [e.g., ritonavir]) may increase plasma concentrations of buprenorphine, possibly resulting in increased or prolonged opiate effects, particularly when an inhibitor is added after a stable buprenorphine dosage has been achieved.1,213 If concomitant use of buprenorphine with drugs that inhibit CYP3A4 is necessary, patients should be monitored at frequent intervals for respiratory depression and sedation, and dosage adjustments should be considered until stable drug effects are achieved.1,213 Discontinuance of a concomitantly used CYP3A4 inhibitor may result in decreased plasma concentrations of buprenorphine, possibly resulting in decreased opiate effects and/or development of opiate withdrawal.1,213 Patients receiving buprenorphine who discontinue therapy with a CYP3A4 inhibitor should be monitored for opiate withdrawal, and dosage adjustments should be considered until stable drug effects are achieved.1,213

Patients who initiate therapy with buprenorphine subdermal implants or buprenorphine extended-release subcutaneous injection after being stabilized on oral transmucosal buprenorphine administered concurrently with a CYP3A4 inhibitor should be monitored to ensure that the plasma buprenorphine concentrations provided by the implants or subcutaneous injection are adequate.236,237 Patients already receiving therapy with buprenorphine implants or buprenorphine extended-release subcutaneous injection who initiate therapy with a CYP3A4 inhibitor should be monitored for manifestations of excessive buprenorphine dosa if there is evidence of buprenorphine toxicity or overdosage and dosage reduction or discontinuance of the concomitant CYP3A4 inhibitor is not feasible, removal of the buprenorphine implants or subcutaneous drug depot and initiation of a buprenorphine formulation that permits dosage adjustments may be necessary.236,237 Conversely, if a CYP3A4 inhibitor is discontinued following stable concomitant therapy with either the implants or extended-release subcutaneous injection, the patient should be monitored for manifestations of withdrawal; if the dosage of buprenorphine from the implants or subcutaneous depot is inadequate in the absence of the CYP3A4 inhibitor, the patient should be switched to a buprenorphine formulation that permits dosage adjustments.236,237

The potential for interactions may depend in part on the route of buprenorphine administration.213 The manufacturer of transdermal buprenorphine states that the pharmacokinetics of buprenorphine administered by the transdermal route are not expected to be affected by concomitant use of CYP3A4 inhibitors.213

CYP3A4 Inducers

Although specific drug interaction studies have not been performed, concomitant use of drugs that induce CYP3A4 (e.g., carbamazepine, phenytoin, rifampin) may reduce plasma concentrations of buprenorphine, possibly resulting in decreased analgesic efficacy and/or development of opiate withdrawal.1,213 If concomitant use of buprenorphine with CYP3A4 inducers is necessary, patients should be monitored for opiate withdrawal, and dosage adjustments should be considered until stable drug effects are achieved.1,213 Discontinuance of a concomitantly used CYP3A4 inducer may result in increased plasma concentrations of buprenorphine, possibly resulting in increased or prolonged therapeutic or adverse effects, including serious respiratory depression.1,213 Patients receiving buprenorphine who discontinue therapy with a CYP3A4 inducer should be monitored for respiratory depression, and the buprenorphine dosage should be adjusted as necessary.1,213

Patients who initiate therapy with buprenorphine subdermal implants or buprenorphine extended-release subcutaneous injection after being stabilized on oral transmucosal buprenorphine administered concurrently with a CYP3A4 inducer should be monitored to ensure that the plasma buprenorphine concentrations provided by the implants or subcutaneous injection are adequate but not excessive.236,237 Patients already receiving therapy with buprenorphine implants or buprenorphine extended-release subcutaneous injection who initiate therapy with a CYP3A4 inducer should be monitored for manifestations of withdrawal; if the dosage of buprenorphine from the implants or subcutaneous injection is inadequate and dosage reduction or discontinuance of the concomitant CYP3A4 inducer is not feasible, the patient should be switched to a buprenorphine formulation that permits dosage adjustments.236,237 Conversely, if a CYP3A4 inducer is discontinued following stable concomitant therapy with either the implants or extended-release subcutaneous injection, the patient should be monitored for manifestations of excessive buprenorphine dosa if the dosage of buprenorphine from the implants or subcutaneous injection is excessive in the absence of the CYP3A4 inducer, removal of the buprenorphine implants or subcutaneous drug depot and initiation of a buprenorphine formulation that permits dosage adjustments may be necessary.236,237

The potential for interactions may depend in part on the route of buprenorphine administration.237

Antifungals

Administration of ketoconazole 400 mg daily in patients receiving stable sublingual doses of buprenorphine in fixed combination with naloxone (buprenorphine/naloxone) increased peak plasma concentrations of buprenorphine by 100% and mean area under the plasma concentration-time curve (AUC) by 75-100% from baseline.251 However, concomitant use of ketoconazole 200 mg twice daily for 11 days and transdermal buprenorphine 10 mcg/hour for 7 days did not affect the pharmacokinetics of buprenorphine.213

Antiretrovirals

Some human immunodeficiency virus (HIV) protease inhibitors (PIs) with CYP3A4 inhibitory activity (i.e., lopinavir in fixed combination with ritonavir [lopinavir/ritonavir], nelfinavir, ritonavir) have been shown to have minimal pharmacokinetic and no clinically important pharmacodynamic interactions with buprenorphine.1,214 However, concomitant use of buprenorphine and other PIs with CYP3A4 inhibitory activity (i.e., unboosted atazanavir, ritonavir-boosted atazanavir) has resulted in increased plasma concentrations of buprenorphine and norbuprenorphine and excessive opiate effects.213,214,224 While concomitant use of ritonavir-boosted atazanavir and buprenorphine is not expected to affect the pharmacokinetics of atazanavir, concomitant use of unboosted atazanavir and buprenorphine may result in decreased plasma atazanavir concentrations.224 The manufacturers of buprenorphine state that patients receiving buprenorphine concomitantly with atazanavir (with or without ritonavir) should be monitored; buprenorphine dosage reduction may be warranted.1,214,224 The manufacturer of atazanavir states that concomitant use of unboosted atazanavir and buprenorphine is not recommended.224 If therapy with ritonavir-boosted or unboosted atazanavir must be initiated in a patient already receiving therapy with buprenorphine subdermal implants or extended-release subcutaneous injection, the patient should be monitored for manifestations of excessive buprenorphine dosa removal of the buprenorphine implants or subcutaneous drug depot and initiation of an alternative buprenorphine formulation that permits dosage adjustments may be necessary.236,237

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are metabolized principally by CYP3A4, and certain NNRTIs may either inhibit (e.g., delavirdine) or induce (e.g., efavirenz, etravirine, nevirapine) CYP3A enzymes.214 Pharmacokinetic interactions have been observed with concomitant use of buprenorphine and certain NNRTIs (i.e., efavirenz, delavirdine).1,214 However, these interactions did not result in substantial pharmacodynamic effects.1,213,214 Patients receiving chronic buprenorphine therapy who begin therapy with an NNRTI should have their buprenorphine dosage monitored.1,214,237

Nucleoside reverse transcriptase inhibitors (NRTIs) do not appear to induce or inhibit CYP enzymes, and interactions with buprenorphine are not expected.1,213,214

Drugs Metabolized by Hepatic Microsomal Enzymes

In vitro studies indicate that buprenorphine inhibits activity of CYP2D6 and CYP3A4 and its major metabolite, norbuprenorphine, is a moderate inhibitor of CYP2D6.214,232 However, the relatively low plasma concentrations of buprenorphine and norbuprenorphine resulting from therapeutic doses of the drug are not expected to result in clinically important interactions.214,232

Drugs that Prolong the QT Interval

Because of the risk of QT-interval prolongation, buprenorphine should be avoided in patients receiving class IA (e.g., quinidine, procainamide, disopyramide) or class III (e.g., sotalol, amiodarone, dofetilide) antiarrhythmic agents or other drugs known to prolong the QT interval.1,213,232,236 (See Cautions: Cardiovascular Effects.)

Drugs Associated with Serotonin Syndrome

Serotonin syndrome may occur in patients receiving opiate partial agonists concomitantly with other serotonergic drugs, including serotonin (5-hydroxytryptamine; 5-HT) type 1 receptor agonists (“triptans”), selective serotonin-reuptake inhibitors (SSRIs), selective serotonin- and norepinephrine-reuptake inhibitors (SNRIs), tricyclic antidepressants, antiemetics that are 5-HT₃ receptor antagonists, buspirone, cyclobenzaprine, dextromethorphan, lithium, St. John's wort ( Hypericum perforatum ), tryptophan, other serotonin modulators (e.g., mirtazapine, nefazodone, trazodone, vilazodone), and monoamine oxidase (MAO) inhibitors (both those used to treat psychiatric disorders and others, such as linezolid, methylene blue, and selegiline).1,213,232,400 Serotonin syndrome may occur within the recommended dosage ranges for these drugs.400 Manifestations of serotonin syndrome may include mental status changes (e.g., agitation, hallucinations, coma), autonomic instability (e.g., tachycardia, labile blood pressure, hyperthermia), neuromuscular aberrations (e.g., hyperreflexia, incoordination, rigidity), and/or GI symptoms (e.g., nausea, vomiting, diarrhea).400 Symptom onset generally occurs within several hours to a few days of concomitant use, but may occur later, particularly after dosage increases.400

If concomitant use of other serotonergic drugs is warranted, patients should be monitored for serotonin syndrome, particularly during initiation of therapy and dosage increases.1,213,232,400 If serotonin syndrome is suspected, treatment with buprenorphine, other opiate agonist or partial agonist therapy, and/or any concurrently administered serotonergic agents should be discontinued.1,213,232,400

Drugs Affecting Hepatic Blood Flow

When buprenorphine is administered concomitantly with a drug(s) that may reduce hepatic blood flow (e.g., halothane) and thereby reduce hepatic elimination of the partial opiate agonist, the activity of buprenorphine may be increased and/or prolonged.1,116,186,191 If such concomitant therapy is administered, buprenorphine should be used with caution and dosage of at least one of the drugs should be reduced.1,186,189

Anticholinergic Agents

Concomitant use of buprenorphine and drugs with anticholinergic activity may increase the risk of urinary retention and/or severe constipation, which can lead to paralytic ileus.1,213 Patients receiving such concomitant therapy should be monitored for signs or symptoms of urinary retention and reduced GI motility.1,213

Diuretics

Opiates may decrease the effects of diuretics by inducing the release of vasopressin (antidiuretic hormone).1,213 Patients receiving such concomitant therapy should be monitored for decreased diuretic or hypotensive effects; dosage of the diuretic may be increased if clinically indicated.1,213

Local Anesthetics

Buprenorphine may potentiate the effects of local anesthetics (e.g., bupivacaine hydrochloride, mepivacaine hydrochloride),24,92 and concomitant administration of the drugs may result in a more rapid onset and prolonged duration of analgesia.24

Monoamine Oxidase Inhibitors

Because concomitant use of opiates with MAO inhibitors (e.g., linezolid, phenelzine, tranylcypromine) may result in serotonin syndrome or manifestations of opiate toxicity (e.g., respiratory depression, coma), use of buprenorphine is not recommended in patients who are receiving or have recently (i.e., within 2 weeks) received an MAO inhibitor.1,213

Neuromuscular Blocking Agents

Buprenorphine may enhance the neuromuscular blocking action and increase the respiratory depressant effect of neuromuscular blocking agents.1,213 Patients receiving such concomitant therapy should be monitored for a greater than expected degree of respiratory depression; dosage of one or both drugs should be decreased as needed.1,213

Opiate Agonists and Partial Agonists

Opiate partial agonists (e.g., butorphanol, nalbuphine, pentazocine) may reduce the analgesic effect of buprenorphine and/or precipitate withdrawal symptoms; such concomitant use should be avoided.1,213

Buprenorphine, which has high affinity but weaker agonistic effects at µ-opiate receptors, can displace full agonists from these receptors, with a resultant reduction in opiate agonist effects; therefore, initiation of buprenorphine therapy in individuals dependent on full opiate agonists before the agonistic effects of the opiate have subsided may precipitate withdrawal.214,247,248 Dosage of the full opiate agonist should be tapered before buprenorphine is initiated for analgesia.213,232 Induction therapy with buprenorphine-containing preparations for opiate dependence should be initiated only when clear and objective signs of withdrawal are evident.214,233,234,235,247,250

Acute Toxicity

Manifestations

Acute overdosage of buprenorphine may produce respiratory depression, CNS depression with somnolence progressing to stupor or coma, cardiovascular manifestations including bradycardia and hypotension, skeletal muscle flaccidity, cold and clammy skin, pinpoint pupils, partial or complete airway obstruction, pulmonary edema, atypical snoring, and death.1,202,213 Marked mydriasis (rather than miosis) may be observed in patients with hypoxia.213

Treatment

In acute buprenorphine overdosage, the patient's respiratory and cardiac status should be monitored carefully.1,20,202 Primary attention should be given to reestablishment of adequate respiratory exchange by maintaining an adequate, patent airway and using assisted or controlled respiration.1,20,202 Other supportive measures, such as oxygen and IV fluids and vasopressors, should also be used as necessary.1,20,202 While doxapram9,18,21,59,70,71,76,84,185 and naloxone9,19,20,21,44,70 may be of value in the management of buprenorphine overdosage, they also may be ineffective in, and therefore should not be relied on for, reversing buprenorphine-induced respiratory depression;1,40,64,192,202 instead, the use of assisted or controlled respiration and administration of oxygen may be necessary and should be considered the principal method of management of buprenorphine overdosage.1,20,46,83,202 When naloxone is used to reverse respiratory depression in patients receiving buprenorphine, larger than usual doses and repeated administration may be necessary.21,194,213

An opiate antagonist (e.g., naloxone, nalmefene) should not be administered in the absence of clinically important respiratory or circulatory depression secondary to buprenorphine overdosage.1 In patients physically dependent on opiates, administration of the usual dose of an opiate antagonist will precipitate acute withdrawal.1 If a decision is made to treat serious respiratory depression in a physically dependent patient with an opiate antagonist, administration should be initiated with care and by titration using smaller than usual doses.1

In cases of acute overdosage involving transdermal buprenorphine, the transdermal system should be removed immediately and the pharmacokinetic profile of transdermal administration should be considered.213 While patients may appear to improve with appropriate supportive measures, there is the possibility of extended buprenorphine effects as the drug continues to be absorbed from the skin.213 After removal of the buprenorphine transdermal system, plasma drug concentrations decrease by 50% in approximately 12 hours (range 10-24 hours) and the apparent terminal half-life is approximately 26 hours.213 The duration of action of transdermal buprenorphine may exceed the duration of action of the opiate antagonist used to treat the overdose.213 Patients may require monitoring and treatment for at least 24 hours after the buprenorphine transdermal system is removed.213

In cases of overdosage potentially involving multiple agents, the potential contribution of buprenorphine versus other CNS depressants should be considered in deciding whether buprenorphine subdermal implants should be removed.237 In an emergency situation, the implants may be removed by a surgeon who is not REMS certified.237 In patients who have received buprenorphine extended-release subcutaneous injection, clinical data are limited regarding possible surgical removal of the subcutaneous drug depot.236

Chronic Toxicity

Patients may develop psychological dependence to the opiate agonist activity of buprenorphine;1,112 however, animal studies suggest that the reinforcing efficacy of buprenorphine may be less than that of the opiate agonists, morphine and codeine, and less than that of the other opiate partial agonists, butorphanol, nalbuphine, and pentazocine.112,190 Limited physical dependence also may occur,41,85,86,107,108,109,111,112,147 although infrequently,74,178 and the potential for development of tolerance to the drug's opiate agonist activity is limited.107,109,171,178,258 Studies in animals have suggested that cross-tolerance between buprenorphine and other opiate agonists (i.e., morphine) may develop.12,178 Studies in animals and humans have also suggested that buprenorphine may have a lesser physical dependence liability than morphine13,21,71,84,87,111,112,145,157 or pentazocine;109,112 however, buprenorphine has been misused by drug abusers and patients physically dependent on opiates in an attempt to substitute the drug for opiate agonists.8,41,85,91,108,133,171,194,198,199

Administration of naloxone in a group of patients who received prolonged therapy with buprenorphine (1-2 months) and who were formerly physically dependent on opiates did not produce withdrawal.71,111 In a group of patients physically dependent on opiates who had substituted buprenorphine for the opiate agonist, discontinuance of buprenorphine slowly over several days resulted in a complete absence of signs and symptoms of withdrawal during the 30-day observation period.107 An initial 0.4-mg IV dose of naloxone produced no evidence of withdrawal in an individual with a history of parenteral misuse of opiate agonists who had substituted IV buprenorphine for the opiate agonist for a 6-month period and in whom a urinalysis confirmed the absence of opiate agonists in the urine; however, additional 2-mg doses of naloxone injected IV every 5 minutes up to a total dose of 10 mg precipitated signs and symptoms of opiate withdrawal which were relieved by administration of IV morphine.85

Signs and symptoms of acute withdrawal following discontinuance of buprenorphine are similar to, but less intense than, those produced by morphine9,71,84,85,111,194 or methadone100 and may include abdominal pain,20,85 nausea,20,71,111 vomiting,20,71,111 restlessness,20,71,85 insomnia,71,85,111 diarrhea,20,71,111 chills,85,111 hot flushes (flashes),111 general aches and pains,85,111 hypertension,85 anorexia,111 malaise,111 tachycardia,85 lacrimation,85,111 rhinorrhea,85,111 diaphoresis,20,85,111 and piloerection.20,85,111 Similar signs and symptoms of withdrawal reportedly occurred following administration of naloxone in an individual with a history of buprenorphine abuse.85 Following abrupt discontinuance of buprenorphine after prolonged use (1-2 months), signs and symptoms of acute withdrawal were delayed and gradually appeared over 3-10 days,71,111,194 reached a peak after about 14 days,21,71,111 and continued for an additional 7-14 days.84,111

Pharmacology

Opiate Agonist and Antagonist Properties

Buprenorphine is an opiate partial agonist1,71,147,148,167,173,178 and shares many of the actions of opiate agonists.1,45,71,82,164,167,178 The drug exhibits analgesic1,71,112,129 and opiate antagonist activities.1,8,71,74,86,111,112,148 Buprenorphine is thought to act as a partial agonist at µ-opiate receptors8,10,112,147,160,173,175,178,189,194,202,213,214 in the CNS8,160 and peripheral tissues.8 The drug also is an antagonist at κ-opiate receptors and an agonist at δ-opiate receptors.202,213,214

Buprenorphine appears to have a high affinity for both µ-1,8,21,161,162,169,175 and κ-receptors,8,162,175 and low to moderate intrinsic activity at µ-8,10,21,160 and κ-receptors;8,160 in contrast, the drug appears to have low to high affinity for8,160,161,162,175 and low intrinsic activity at8δ-receptors. Buprenorphine binds slowly with10,169 and dissociates slowly from the µ-receptor.1,8,10,169,178,179 It is thought that the high affinity of buprenorphine for the µ-receptor and its slow binding to and dissociation from the receptor may account for the prolonged duration of analgesia1,157,179 and possibly in part for the limited physical dependence potential observed with the drug.1,8,10,157,178

The opiate agonist and antagonist activities of buprenorphine appear to be dose related.160,163,165 At doses of up to 1 mg subcutaneously, buprenorphine has a potent analgesic effect;71,160,163,165 at doses greater than 1 mg subcutaneously, the opiate agonist activity of the drug decreases and the opiate antagonist activity predominates.71,160,163,165 Following IM administration, the opiate antagonist activity of buprenorphine occurs principally at doses greater than 0.8 mg.71,160,163 The drug may antagonize its own opiate agonist activity when administered at doses within the opiate antagonist range.165,193

Animal studies have shown that antagonism of the opiate agonist activity of buprenorphine by other opiate antagonists may not occur once buprenorphine binds to opiate receptors in the CNS.8,10,159 In animals not physically dependent on opiates, administration of an opiate antagonist (e.g., naloxone) prior to or concomitantly with administration of buprenorphine results in a reduction or complete block of buprenorphine-induced opiate agonist activity.10,17,71,159,178 When buprenorphine is administered prior to an opiate antagonist, the agonist activity of buprenorphine is dominant.10,17,71,159,178 Similarly, administration of naloxone in a group of patients receiving prolonged therapy with buprenorphine (1-2 months) did not precipitate withdrawal.71,111

On a weight basis, the opiate antagonist activity of buprenorphine is reportedly equal to1,12,183,194 or up to 3 times greater than67 that of naloxone when both drugs are compared as antagonists of morphine. Buprenorphine may precipitate mild to moderate withdrawal in some patients physically dependent on opiates.1,87,100,112,147,194 In patients who have received single subcutaneous morphine doses of up to 120 mg during chronic buprenorphine therapy,111 buprenorphine produces a block of the pharmacologic effects of morphine.71,111 Buprenorphine reportedly does not antagonize respiratory depression produced by non-opiate analgesics and other drugs.13

Repeated exposure to short-acting opiates appears to result in neurobiologic changes in cellular and molecular systems; these changes include perturbations in opiate-receptor kinetics, transmembrane signaling, postreceptor signal transduction, and intracellular messengers.207,208 The physiologic dependence and addictive behavior that are characteristic of opiate dependence result from these neurobiologic changes and are the basis for use of opiate agonists for the treatment of opiate dependence.207,208 Opiate agonists stabilize brain neurochemistry by replacing short-acting euphorigenic opiates (e.g., heroin) with long-acting noneuphorigenic opiates (e.g., buprenorphine, levomethadyl acetate hydrochloride [no longer commercially available in the US], methadone).207 The mechanism(s) of action of these long-acting noneuphorigenic opiates include cross-tolerance at the opiate receptor, thus preventing opiate withdrawal, and competition for opiate-receptor binding sites, thus blocking the effects of exogenously administered opiates.207

Like opiate agonists such as methadone or hydromorphone, sublingual administration of buprenorphine produces typical opiate agonist effects, which are limited by a ceiling effect.202 In individuals who were not opiate dependent, administration of a single sublingual dose of buprenorphine produced opiate agonist effects; these effects were maximal at doses of 8-16 mg.202 The effect of buprenorphine 16 mg was similar to that of an equivalent dose of buprenorphine given in fixed combination with naloxone.251

Administration of single doses of buprenorphine produce physiologic and subjective effects that are similar to those produced by equivalent doses of buprenorphine administered in fixed combination with naloxone.202 When administered sublingually, the naloxone in fixed combination with buprenorphine does not have any clinically important pharmacologic effects.202 Buprenorphine in fixed combination with naloxone is recognized as an opiate agonist in opiate-dependent individuals when the preparation is given sublingually.202 However, parenteral administration of buprenorphine in conjunction with naloxone results in opiate antagonist actions similar to those of naloxone.202 IV administration of buprenorphine in conjunction with naloxone precipitates opiate withdrawal symptoms in opiate-dependent individuals.202

CNS Effects

Like other opiate agonists,71 buprenorphine produces dose-related analgesia.67,118,128,129 The exact mechanism has not been fully elucidated,1 but analgesia appears to result from a high affinity of buprenorphine for µ- and possibly κ-opiate receptors in the CNS.1,8,10,112,117,147,160,173,176,178,213 The drug may also alter the pain threshold (threshold of afferent nerve endings to noxious stimuli).71 On a weight basis, the analgesic potency of parenteral buprenorphine appears to be about 25-50, 200, and 600 times that of parenteral morphine,1,7,9,10,44,67,71,72,73,77,111,112,178,183,185,194 pentazocine,79 and meperidine,68 respectively. Buprenorphine may produce sex-related differences in analgesia,83,118,129 with females requiring substantially less drug than males to produce adequate analgesia.83,129 Following IV doses of 4 mcg/kg and higher, the drug may produce amnesia.177

In patients physically dependent on opiates, buprenorphine produces many of the subjective and objective effects of opiates;11,74,107,109,111,195,196 however, the drug may not be a satisfactory substitute for opiate agonists for pain relief in all patients physically dependent on opiates.8,100 The potential for development of tolerance to the drug's opiate agonist activity is limited.107,109,171,178,258

Buprenorphine may produce psychological dependence.1,112 Buprenorphine may also produce limited physical dependence,41,85,86,107,108,109,111,112,147,194 although infrequently.1,74 Signs and symptoms of mild withdrawal may appear following discontinuance of prolonged therapy with the drug alone.71,84,100,112,194 (See Chronic Toxicity.) Because buprenorphine binds slowly with10,169 and dissociates slowly from the µ-receptor,1,8,10,169,178,179 elimination of the drug from the CNS is prolonged following abrupt discontinuance; consequently, signs and symptoms of acute withdrawal are less intense than those produced by morphine9,71,84,85,111,194 and delayed in appearance.21,71,111,194 Buprenorphine is a partial opiate agonist with behavioral and psychic effects similar to morphine, and, unlike pentazocine, it rarely causes psychotomimetic effects.40,87

Like other opiate agonists, buprenorphine may produce increases in intracranial pressure.1,213

In rats, buprenorphine produces dose-related changes in the EEG pattern, and changes appear to be maximal at doses of 1 mg/kg.165 Increasing doses up to 1 mg/kg produce intense stupor and continuous high-voltage bursting activity, while doses of 0.3 and 10 mg/kg produce less intense stupor and intermittent bursting activity.165 In rabbits, buprenorphine produces EEG patterns characterized by increases in delta and theta wave activity.71 When administered in daily subcutaneous doses of 2 mg in individuals formerly receiving methadone, buprenorphine therapy was associated with EEG patterns characterized by an increase in alpha wave activity; however, the increase in activity may have resulted from a return of normal EEG patterns following discontinuance of methadone.100 Upon discontinuance of buprenorphine, the EEG pattern was characterized by a decrease in alpha wave activity;100 an increase in alpha wave activity was subsequently observed about 20 days following discontinuance of buprenorphine.100

Cardiovascular Effects

Buprenorphine generally produces few cardiovascular effects.10,21,71,150,185 In healthy individuals, cardiovascular effects induced by parenteral buprenorphine are similar to those following equivalent parenteral doses of morphine, including decreases in heart rate and systolic and diastolic blood pressures.45,71,82 Cardiovascular effects of buprenorphine appear to be of minor clinical importance in most patients,71 including patients with compromised cardiac function who have undergone surgery66,71,141 or patients who are recovering from myocardial infarction.71,150 In a limited number of patients, buprenorphine has been reported to inhibit cardiovascular effects that occur during surgery (e.g., increases in heart rate and systolic blood pressure).135

Buprenorphine may decrease heart rate1,44,45,71,80,82,111,135,185 and systolic and/or diastolic blood pressure.1,45,71,80,82,89,111,150 The drug has also been shown to increase heart rate1,78,177 and blood pressure (principally systolic pressure) in some patients.1 Stroke volume and cardiac output may be slightly increased71 or decreased.45 Buprenorphine produces peripheral vasodilation, which may result in orthostatic hypotension or syncope.1 Cardiovascular effects of buprenorphine, including changes in heart rate, stroke volume, and systolic blood pressure, may be dose related;71 in several studies, buprenorphine-induced cardiovascular effects were not apparent at IV doses of 1.5 mcg/kg but appeared at IV doses of 2 mcg/kg and higher.71,141

Prolongation of the QT interval was observed in healthy individuals receiving transdermal buprenorphine at dosages of 40 mcg/hour; dosages of 10 mcg/hour did not result in clinically relevant changes in the QT interval.213,232 Prolongation of the QT interval also was observed in patients receiving buprenorphine buccally dissolving strips at dosages of up to 900 mcg every 12 hours.

Respiratory Effects

Usual parenteral doses of buprenorphine potentially may depress respiration to the same degree as 10 mg of parenteral morphine sulfate.1,71 The onset of buprenorphine-induced respiratory depression is slower than that of morphine-induced respiratory depression and the duration appears to be more prolonged.71 Respiratory depression may be severe in individuals with compromised respiratory function or those receiving other respiratory depressant drugs concomitantly.1,71

Buprenorphine-induced respiratory depression is dose related in single parenteral doses of up to 1.2 mg.1,21,70,71,89,173 Unlike morphine, there appears to be a ceiling to buprenorphine-induced respiratory depression in most patients,21,71,118,173,178 so that higher doses of the drug do not necessarily produce a proportionate increase in respiratory depression.71,118,129 Changes in frequency, depth, and pattern of respiration and changes in arterial blood gas values do not appear to be clinically important in most patients.110,178 However, in animal studies, concomitant use of buprenorphine with benzodiazepines appeared to alter the usual ceiling on buprenorphine-induced respiratory depression, resulting in respiratory depressant effects similar to those of full opiate agonists.213

Buprenorphine-induced respiratory depression is characterized by decreases in arterial Po₂73,129 and rate of respiration18,44,48,58,71,73,129,192 and increases in arterial Pco₂.18,48,58,73,92,192

IV naloxone hydrochloride has been used to reverse signs of buprenorphine-induced respiratory depression;1,9,19,20,21,44,70 however, in usual doses, naloxone is substantially less effective in reversing buprenorphine-induced respiratory depression9,19,21 than in reversing morphine-induced respiratory depression19,21 and is occasionally only partially effective9,21,40,71,84 and, rarely, completely ineffective1,40,64,192,194 in reversing buprenorphine-induced respiratory depression. When naloxone is used to reverse signs of respiratory depression in patients receiving buprenorphine, larger than usual doses may be necessary.21,194,213 Doxapram has also been used with some success in reversing buprenorphine-induced respiratory depression.9,18,21,59,70,71,76,84,185

The effect of buprenorphine on the cough reflex in humans has not been studied;186 however, in guinea pigs, the drug suppresses experimentally induced cough.17

Endocrine Effects

Like other opiate agonists,164,168 buprenorphine has been shown to decrease plasma concentrations of luteinizing hormone (LH)118,164 and increase plasma concentrations of prolactin.83,118,164,167 Buprenorphine has been reported to prevent the stress-induced increase in plasma cortisol concentration that occurs during surgery;83,129,166,172 however, the drug has also been reported to lack an inhibitory effect on surgery-induced increases in plasma cortisol in other patients70,83,158 and to increase plasma cortisol in healthy individuals.167 In some patients, the drug did not inhibit increases in plasma glucose concentration,83,129,158 but in other patients it reportedly prevented increases in plasma glucose concentration.83,166 Buprenorphine has been shown to reverse surgery-induced increases in plasma growth hormone (GH) and insulin concentrations,166 but the drug has produced increases in plasma GH concentration in healthy individuals.167

GI Effects

Buprenorphine produces minimal GI effects, including nausea,1,40,44,49,51,53,67,71,76,79,83,93,105,106,185,192 vomiting,1,27,40,44,51,53,67,71,83,93,105,106,185,192 and constipation.1,74,97,107,111 Like other opiate agonists, buprenorphine may produce an increase in pressure within the common bile duct,1,21,40,52,54 which may be followed by a rapid decrease in pressure.21,52 In healthy individuals, the drug did not alter baseline pressure of the sphincter of Oddi, and flow of biliary and pancreatic fluids was unaffected.156

Other Effects

Buprenorphine causes dose-related miosis,1,18,67,74,89,111,118,174 with peak miotic effects occurring at 6 hours71,111,174,192 and miosis continuing for about 72 hours after parenteral administration.71,111

Buprenorphine produces urinary retention in some patients.1,71,92,101,107,111,213

Pharmacokinetics

Absorption

Some pharmacokinetic data indicate that a relationship between plasma buprenorphine concentrations and a given analgesic effect does not exist.116,130

Buprenorphine Hydrochloride Conventional Injection

Buprenorphine hydrochloride is rapidly and approximately 40-90% absorbed systemically following IM administration.116,118

Following IV administration of a single 0.3-mg dose of buprenorphine, mean peak plasma drug concentrations of 18 ng/mL116 occurred within 2 minutes;116,118 plasma concentrations declined to 9 and 0.4 ng/mL after 5 minutes and 3 hours, respectively.116 Following IM administration of a second 0.3-mg dose 3 hours after the initial IV dose, mean peak plasma buprenorphine concentrations of 3.6 ng/mL occurred within 2-5 minutes9,116,118 and declined to 0.4 ng/mL after 3 hours.116 Approximately 10 minutes after administration, plasma concentrations of buprenorphine are similar following IV or IM injection.9,116,118 Plasma concentrations of buprenorphine may be increased slightly by concomitant administration of a general anesthetic (e.g., halothane) as a result of anesthesia-induced decrease in hepatic blood flow and hepatic clearance of the drug.116

Following IM or IV administration of a single dose of buprenorphine, onset of analgesia is similar to that following IM or IV administration of morphine, respectively;71,128,183,185 the time of peak analgesia is similar to that of parenteral morphine,71,97,128,145,177,185 meperidine,71,80 or pentazocine.177 The onset of analgesia and time to peak analgesia are shorter following IV administration of buprenorphine than IM administration.1 The duration of analgesia produced by parenteral buprenorphine is longer than that produced by parenteral meperidine21,71,80,98,184 or pentazocine21,48,71,177 and is comparable to128,145,185 and, in some patients, may be longer than that produced by parenteral morphine.21,71,82,97,128,152,177,185 The duration of analgesia may vary according to the route of administration, with a more prolonged duration following IV71,80 or epidural30,92 administration than IM administration.16,71,123,124 The duration of analgesia may be prolonged with higher doses of buprenorphine;92,110,129 however, duration of analgesia did not differ substantially in a group of patients receiving 0.15- to 0.4-mg doses of the drug.128 The duration of analgesia induced by buprenorphine may also be affected by patient age, with the duration slightly prolonged in older patients.121 Following parenteral administration of single doses of 0.15-0.6 mg or 2-12 mcg/kg of buprenorphine in postoperative patients,9,16,21,42,48,71,72,80,82,96,97,98,121,123,124,127,128 the onset of analgesia usually occurs within 10-30 minutes,1,9,16,17,96,123,124,128,185 and peak analgesia usually occurs within 60 minutes;1,71,80,96,128,185 however, peak analgesia may occur within as little as 15 minutes in some patients.71 The mean duration of analgesia generally is 6 hours following single IM or IV doses of 0.2-0.3 mg or 2-4 mcg/kg;1,16,21,71,72,82,96,121,124,185 however, in some studies, the mean duration of analgesia reportedly ranged from 4-10 hours following single IM doses of 0.2-0.6 mg16,21,71,72,82,96,97,98,123,124,127,184 and 2-24 hours following single IV doses of 0.3 mg or 2-15 mcg/kg.42,48,71,80,121,152

Buprenorphine Transdermal System

When administered transdermally, buprenorphine has an absolute bioavailability of approximately 15%.213 Following application of a single transdermal system delivering buprenorphine 5, 10, or 20 mcg/hour, peak plasma concentrations of buprenorphine average 0.176, 0.191, or 0.471 ng/mL, respectively.213 Quantifiable buprenorphine concentrations are detectable approximately 17 hours after placement of the 10-mcg/hour transdermal system, with steady-state concentrations attained by the third day of treatment.213 Blood concentrations of buprenorphine increased by 26-55% when heat was applied directly to a transdermal system designed to deliver the drug at a dosage of 10 mcg/hour; concentrations returned to normal within 5 hours after the heat source was removed.213

Oral Transmucosal Formulations Used for Analgesia

Following administration of a single dose of buprenorphine (75-1200 mcg) as a buccally dissolving strip (Belbuca^®), absolute bioavailability is 46-65% and peak plasma concentrations and AUC increase in a linear manner.232 Following single doses of 75, 300, or 1200 mcg, peak plasma concentrations of buprenorphine average 0.17, 0.47, or 1.43 ng/mL, respectively, and are achieved at a median of 2.5-3 hours.232 Following repeated administration at a dosage of 60-240 mcg every 12 hours, steady-state plasma concentrations are attained prior to the sixth dose, and steady-state peak plasma concentrations and AUC are proportional to dose.232

Ingestion of cold, hot, or room-temperature water during buccal administration of the strips decreased systemic exposure to buprenorphine by 23-27%; concurrent ingestion of a low-pH liquid such as decaffeinated cola decreased systemic exposure to the drug by approximately 37%.232

In cancer patients with grade 3 mucositis, absorption of buprenorphine from the buccally dissolving strips was more rapid and peak plasma concentrations and AUC were approximately 79 and 56% higher, respectively, compared with healthy controls.232

Oral Transmucosal Formulations Used for Treatment of Opiate Dependence

Not all formulations, strengths, or dose combinations of oral transmucosal preparations containing buprenorphine in fixed combination with naloxone (buprenorphine/naloxone) are bioequivalent.202,214,234,235

Following sublingual administration of generic buprenorphine or buprenorphine/naloxone sublingual tablets (i.e., generic equivalents of Subutex^® or Suboxone^® sublingual tablets [branded formulations no longer commercially available in the US]), there is substantial interindividual variability in absorption of the drugs, but intraindividual variability is low.202,233 Peak plasma concentrations and AUC of buprenorphine increase with increasing dose (over the range of 4-16 mg), but the increase is not directly proportional to dose.202,233 Following sublingual administration of buprenorphine sublingual tablets at a dose of 2, 8, or 16 mg, peak plasma buprenorphine concentrations average 1.25, 2.88, or 4.7 ng/mL, respectively.233 Following sublingual administration of a single tablet containing buprenorphine 2 mg and naloxone 0.5 mg or containing buprenorphine 8 mg and naloxone 2 mg, peak plasma buprenorphine concentrations average 0.78 or 2.58 ng/mL, respectively.202 In most individuals, quantifiable amounts of naloxone are not detected in plasma beyond 2 hours after sublingual administration of buprenorphine/naloxone at naloxone doses of 1-4 mg; mean peak plasma concentrations of naloxone at these doses range from 0.11-0.28 ng/mL.202

Not all strengths and combinations of buprenorphine/naloxone (Suboxone^®) sublingually dissolving strips are bioequivalent to Suboxone^® sublingual tablets administered at the same total dose.214 A dose consisting of one or two strips, each containing buprenorphine 2 mg and naloxone 0.5 mg, administered sublingually or buccally showed comparable relative bioavailability to sublingual tablets providing the same total dose.214 However, at a strength of buprenorphine 8 mg in fixed combination with naloxone 2 mg or a strength of buprenorphine 12 mg in fixed combination with naloxone 3 mg, a single strip administered sublingually or buccally showed higher relative bioavailability for both buprenorphine and naloxone compared with sublingual tablets providing the same total dose.214 A combination of one strip containing buprenorphine 8 mg and naloxone 2 mg and two strips containing buprenorphine 2 mg and naloxone 0.5 mg (total dose of buprenorphine 12 mg and naloxone 3 mg) administered sublingually showed comparable relative bioavailability as sublingual tablets providing the same total dose; however, when the strips were administered buccally, relative bioavailability was higher than that of the sublingual tablets.214 Pharmacokinetic parameters and systemic exposures are generally comparable following either buccal or sublingual administration of buprenorphine/naloxone strips, although systemic exposure to naloxone may be somewhat higher after buccal administration.214

Buprenorphine/naloxone (Zubsolv^®) sublingual tablets are not bioequivalent to Suboxone^® sublingual tablets.235 One Zubsolv^® sublingual tablet containing buprenorphine 5.7 mg and naloxone 1.4 mg provides 12% lower naloxone exposure and equivalent buprenorphine exposure as one Suboxone^® sublingual tablet containing buprenorphine 8 mg and naloxone 2 mg.235 Although there is substantial interindividual variability in absorption of buprenorphine and naloxone from Zubsolv^® sublingual tablets, intraindividual variability is low.235 Peak plasma concentrations and AUC of buprenorphine increase with increasing dose (over the range of 1.4-11.4 mg), but the increase is not directly proportional to dose.235

Buprenorphine/naloxone (Bunavail^®) buccally dissolving strips are not bioequivalent to Suboxone^® sublingual tablets.234 One buccally dissolving strip containing buprenorphine 4.2 mg and naloxone 0.7 mg provides 33% lower naloxone exposure and equivalent buprenorphine exposure as one sublingual tablet containing buprenorphine 8 mg and naloxone 2 mg.234 Although there is substantial interindividual variability in buccal absorption of buprenorphine and naloxone from Bunavail^® strips, intraindividual variability is low.234 Peak plasma concentrations and AUC of buprenorphine increase with increasing dose (over the range of 0.875-6.3 mg), but the increase is not directly proportional to dose.234 Administration of liquids with the strips reduces systemic exposure to both buprenorphine and naloxone by as much as 59 and 76%, respectively, depending on the pH of the liquid.234

Concomitant administration of naloxone and buprenorphine does not affect the pharmacokinetics of buprenorphine.202,234,235

Buprenorphine Extended-release Subcutaneous Injection

Following subcutaneous administration of buprenorphine extended-release injection, a solid depot forms and the drug is released via diffusion from and biodegradation of the depot.236 Following administration of single doses of 50-200 mg and repeated doses of 50-300 mg at 28-day intervals, initial peak plasma concentrations of the drug were attained at a median of 24 hours after injection; concentrations then decreased slowly to a plateau, and steady-state concentrations were achieved at 4-6 months.236 Mean steady-state plasma concentrations attained following 6 doses of the extended-release subcutaneous injection (a series of two 300-mg doses followed by four 100-mg doses or a series of six 300-mg doses) administered at 28-day intervals were 3.21 or 6.54 ng/mL, respectively, compared with 2.91 ng/mL following stabilization on a buprenorphine dosage of 24 mg daily as sublingual tablets.236 At steady state, mean trough plasma concentrations achieved with both subcutaneous dosages and the mean peak concentration achieved with the higher-dosage subcutaneous regimen exceeded those attained with the sublingual dosa the peak concentration attained with the lower-dosage subcutaneous regimen was approximately 59% of that attained with the sublingual dosage.236 Pharmacokinetic simulations suggest that therapeutic concentrations of the drug persist for 2-5 months, depending on the dosage (100 or 300 mg monthly), following the last injection of the drug.236

Buprenorphine Hydrochloride Subdermal Implants

Following insertion of buprenorphine hydrochloride subdermal implants, initial peak plasma concentrations of the drug were attained at a median of 12 hours after insertion; concentrations then decreased slowly, and steady-state concentrations were achieved by approximately week 4.237 Mean steady-state plasma concentrations of approximately 0.5-1 ng/mL were maintained for approximately 20 weeks (weeks 4-24) and were comparable to the steady-state trough buprenorphine concentrations attained with a sublingual buprenorphine dosage of 8 mg daily.237 In one study in patients who received sublingual buprenorphine (16 mg daily for at least 5 days) followed by insertion of 4 implants (total buprenorphine hydrochloride dose of 320 mg), overall peak plasma concentrations of buprenorphine were markedly lower after implant insertion compared with the sublingual dosing lead-in period.237 On day 28 of implant therapy, the steady-state AUC was 31% of the steady-state AUC achieved with the sublingual dosage, and the mean steady-state drug concentration was approximately 0.82 ng/mL (8% of the peak concentration and 52% of the trough concentration achieved at steady state with the sublingual dosage).237

Distribution

Distribution of buprenorphine into human body tissues and fluids has not been well characterized.63,117,120 Following oral or IM administration in rats, buprenorphine distributes into the liver, brain, placenta, and GI tract; highest concentrations were attained in the liver within 10 or 40 minutes following oral or IM administration, respectively.71 The hepatic extraction ratio of buprenorphine (E_H) is approximately 1.116 The drug and its metabolites are distributed into bile.113,213 Following IV administration in humans, the drug rapidly distributes into CSF63,117,120 (within several minutes).117 CSF buprenorphine concentrations appear to be approximately 15-25% of concurrent plasma concentrations.117,213

The volume of distribution of buprenorphine following IV administration in adults is approximately 430 L.213

Buprenorphine is approximately 96% bound to plasma proteins,15,71,213 mainly to α- and β-globulins.71,213

Buprenorphine crosses the placenta71 and distributes into milk.1,213,252

Elimination

Plasma concentrations of buprenorphine generally appear to decline in a triphasic manner.114,116,118 Following IV administration of a single dose in postoperative patients with normal renal and hepatic function, the plasma half-life of buprenorphine reportedly averages 2 minutes in the initial (distribution) phase,40,116,118 11 minutes in the second (redistribution) phase,116 and 2.2 hours (range: 1.2-7.2 hours) in the terminal (elimination) phase.1,21,40,118,119 Some pharmacokinetic data indicate that plasma concentrations of buprenorphine may decline in a biphasic manner in some patients.116,118

Buprenorphine reportedly has a mean elimination half-life of 31-35 hours following sublingual administration as buprenorphine sublingual tablets,233 24-42 hours following sublingual administration as buprenorphine/naloxone sublingual tablets or sublingual or buccal administration as buprenorphine/naloxone sublingually dissolving strips,202,214,235 16-28 hours following buccal administration as buprenorphine/naloxone buccally dissolving strips,234 and 28 hours following buccal administration as buprenorphine buccally dissolving strips.232 Following transdermal administration, the terminal elimination half-life of buprenorphine is approximately 26 hours.213 Following administration as an extended-release subcutaneous injection, buprenorphine has an apparent elimination half-life of 43-60 days as a result of slow release from the subcutaneous depot.236

Buprenorphine is almost completely metabolized in the liver,21,116 principally by N -dealkylation, to form norbuprenorphine ( N -dealkylbuprenorphine).1,71,113,114,115,118,122,125,202 The N -dealkylation pathway is mediated by the cytochrome P-450 (CYP) 3A4 isoenzyme.1,202 Buprenorphine and norbuprenorphine also undergo conjugation with glucuronic acid.1,71,118,122,125 Buprenorphine is conjugated by uridine diphosphate-glucuronosyltransferase (UGT) isoenzymes, mainly UGT 1A1 and 2B7, to form buprenorphine 3- O -glucuronide; norbuprenorphine also is conjugated, mainly by UGT 1A3.213 Following oral administration, buprenorphine appears to undergo extensive first-pass metabolism in the GI mucosa and liver.122,131 Following transdermal administration, buprenorphine undergoes negligible metabolism in the skin.213

Norbuprenorphine binds to opiate receptors in vitro, but it is not known whether norbuprenorphine contributes to the overall effects of buprenorphine.232,233 The AUC ratio of norbuprenorphine to buprenorphine is reportedly 0.2-0.4 at steady state following administration of buprenorphine extended-release subcutaneous injection and approximately 0.36-0.45 following sublingual administration of buprenorphine sublingual tablets.233,236 A norbuprenorphine half-life of 12-21 hours has been reported following sublingual administration of buprenorphine sublingual tablets.233

Buprenorphine and its metabolites are excreted principally in feces (about 69%)113,202,214 via biliary elimination113 and also in urine (about 30%),114,122,170,202,214 almost entirely as unchanged drug, norbuprenorphine, and 2 unidentified metabolites.202,214 Most of the buprenorphine and norbuprenorphine excreted in urine is conjugated (buprenorphine: 1% unconjugated and 9.4% conjugated; norbuprenorphine: 2.7% unconjugated and 11% conjugated), whereas most of the buprenorphine and norbuprenorphine excreted in feces is unconjugated (buprenorphine: 33% unconjugated and 5% conjugated; norbuprenorphine: 21% unconjugated and 2% conjugated).202,214 Buprenorphine and its metabolites are believed to undergo enterohepatic circulation.113,122,170 Following IM administration of a 2-mcg/kg dose of buprenorphine, approximately 70% of the dose is excreted in feces and 27% in urine within 7 days.71,213 Following IV administration of a 0.6-mg dose, about 30% of the dose is excreted in urine within 7 days; approximately 9 and 8% of the dose are excreted in urine as buprenorphine (almost completely as conjugated drug) and norbuprenorphine (mainly as conjugated norbuprenorphine), respectively, within 4 days.114

Reductions in hepatic blood flow induced by some general anesthetics (e.g., halothane) and other drugs may result in a decreased rate of hepatic elimination of buprenorphine.1,116 Plasma clearance of the drug is substantially reduced to 0.9 L/minute following IV administration of a single 0.3-mg dose in patients undergoing nitrous oxide and halothane anesthesia.116,118

Limited data indicate that there is considerable interindividual variability in buprenorphine pharmacokinetics in children; however, clearance of the drug appears to be increased in children (e.g., those 5-7 years of age) compared with that in adults.1 Optimal dosing interval of buprenorphine may have to be decreased in pediatric patients.1

No substantial relationship between estimated creatinine clearance and steady-state buprenorphine concentrations has been observed.213,236 Following IV administration, no differences in pharmacokinetics of buprenorphine have been observed between patients with renal impairment or renal failure requiring dialysis and those with normal renal function.213,236 In dialysis-dependent patients receiving transdermal buprenorphine, predialysis and postdialysis concentrations of the drug were not substantially different.213

Following sublingual administration of a single buprenorphine/naloxone sublingual tablet (buprenorphine 2 mg and naloxone 0.5 mg) in patients with hepatic impairment, no clinically important changes in peak plasma concentrations, systemic exposures, and half-lives of buprenorphine or naloxone were observed in those with mild hepatic impairment.202 However, pharmacokinetics of the drugs were altered in patients with moderate or severe hepatic impairment; naloxone was affected to a greater degree than buprenorphine, and the magnitude of the difference in effect was greater in individuals with severe hepatic impairment than in those with moderate hepatic impairment.202 In those with moderate hepatic impairment, peak plasma concentrations of buprenorphine and naloxone were increased by 8 and 170%, respectively; AUC was increased by 64 and 218%, respectively; and half-life was increased by 35 and 165%, respectively, compared with individuals with normal hepatic function.202 In those with severe hepatic impairment, peak plasma concentrations of buprenorphine and naloxone were increased by 72 and 1030%, respectively; AUC was increased by 181 and 1302%, respectively; and half-life was increased by 57 and 122%, respectively.202

The effects of hepatic impairment on the pharmacokinetics of buprenorphine administered as a 0.3-mg IV infusion have been evaluated in a limited number of patients with mild or moderate hepatic impairment (Child-Pugh class A or B).213 Exposure to buprenorphine and norbuprenorphine was not increased in such patients when compared with patients with normal hepatic function.213 Buprenorphine transdermal system and buprenorphine buccally dissolving strips have not been evaluated in patients with severe hepatic impairment (Child-Pugh class C).213,232 Data are lacking on the effects of hepatic impairment on the pharmacokinetics of buprenorphine administered as subdermal implants or as an extended-release subcutaneous injection.236,237

In patients with hepatitis C virus (HCV) infection without evidence of hepatic impairment, no clinically important changes in peak plasma concentrations, systemic exposure, and half-lives of buprenorphine or naloxone were observed.214

Chemistry and Stability

Chemistry

Buprenorphine is a synthetic partial opiate agonist analgesic that is structurally related to morphine and pharmacologically similar to other currently available opiate partial agonists.1,6,7,10,11,13,14

Buprenorphine hydrochloride occurs as a white,1,5,9 crystalline powder5,6,9 and has solubilities of 17 mg/mL in water (pH 4.4) at 25°C186 and 42 mg/mL in alcohol at room temperature.186 The drug has pK_as of 8.24-8.42 (amine) and 9.92-10 (phenol).15 Commercially available buprenorphine hydrochloride injection is a sterile1 solution of the drug in 5% dextrose injection.1,186 The injection occurs as a clear1 solution186 and has an osmolality of 297 mOsm/kg.187

Potency of buprenorphine hydrochloride is expressed in terms of buprenorphine, calculated on the anhydrous basis.1

The Sublocade^® extended-release subcutaneous injection contains buprenorphine (18% by weight) dissolved in a biodegradable vehicle (Atrigel^®) containing poly(d,l-lactide coglycolide) polymer and N -methyl-2-pyrrolidone (NMP) solvent in a 50:50 ratio.236 Following subcutaneous injection, precipitation of the polymer results in formation of a solid depot; buprenorphine is released from the depot at a controlled rate over one month via diffusion from and biodegradation of the depot.236

Each Probuphine^® implant is a soft, flexible rod (26 mm in length and 2.5 mm in diameter) that contains 80 mg of buprenorphine hydrochloride (equivalent to 74.2 mg of the base) and ethylene vinyl acetate.237 It is designed to be implanted subdermally and to provide sustained delivery of the drug for up to 6 months.237

The Butrans^® transdermal system consists of an outer web backing layer, an adhesive rim that does not contain buprenorphine, a separating layer over the buprenorphine-containing adhesive matrix, and a buprenorphine-containing adhesive matrix.213 The adhesive layer is covered by a protective strip that is removed prior to application.213 The amount of buprenorphine released from each system per hour is proportional to the surface area; release of the drug is designed to occur at an average rate of 5 mcg/hour per 6.25 cm².213 The total buprenorphine content in each 5-, 7.5-, 10-, 15-, and 20-mcg/hour system is 5, 7.5, 10, 15, and 20 mg, respectively.213

Stability

Buprenorphine hydrochloride injection should be protected from prolonged exposure to light and stored at a temperature of 20-25°C, but may be exposed to temperatures ranging from 15-30°C.1

Oral transmucosal preparations of buprenorphine hydrochloride (sublingual tablets, buccally dissolving strips) or buprenorphine hydrochloride in fixed combination with naloxone hydrochloride (sublingual tablets, sublingually dissolving strips, buccally dissolving strips) should be stored at room temperature (generally 20-25°C, but may be exposed to temperatures ranging from 15-30°C).202,214,232,233,234,235 Sublingually or buccally dissolving strips should be used immediately after removal from the individually sealed packa strips that have been altered (e.g., torn, cut, damaged) should not be used.214,232,234 Bunavail^® buccally dissolving strips should be protected from freezing and moisture.234

Buprenorphine extended-release subcutaneous injection should be stored at 2-8°C.236 After removal from the refrigerator, the injection may be stored in its original package at 15-30°C for up to 7 days prior to administration; if not used within 7 days, the injection should be discarded.236

Kits containing buprenorphine hydrochloride implants should be stored at 20-25°C, but may be exposed to temperatures ranging from 15-30°C.237

Buprenorphine transdermal systems should be stored at 25°C, but may be exposed to temperatures ranging from 15-30°C.213 The system should be applied to the skin immediately after removal from the individually sealed package, and should be discarded if the seal was previously broken.213 Transdermal systems that have been cut, damaged, or altered in any way should be discarded since use of such systems may expose the patient or caregiver to the contents of the system and result in a potentially lethal overdose of the drug.213

Buprenorphine preparations should be stored in a secure place to prevent access by children.213,232

1. Indivior Inc. Buprenex^® (buprenorphine hydrochloride) injection prescribing information. North Chesterfield, VA; 2018 Jan.

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